Communism doesn't work because is out-competed by mixed economy socialism.
The coalition of nations that opposed the USSR and won was made up entirely of mixed-economies, free market systems with large government regulation, and national infrastructure and income redistribution programs.
All successful countries today are "socialist."
Nothing can compete with the mixed economy. It lacks the suicidal excesses of the purer ideologies.
= new reply since forum marked as read
Remember, people often adopt a dogma that justifies their position of society, and if that means adopting a dogma that means everyone for him or herself, those that benefit will embrace such a dogma (thus the radical adoption of the right wing and "Neo-Liberal" Economic theory" and it is these people that I am referring to as "Radical Capitalists"
Communism tend to be a reaction to Radical capitalism, and as a reaction they go to far in the other direction. Often this is necessary for without that radical turn, the Radical Capitalists just fight the Socialists for the Radical Capitalists see the Socialist as the "Enemy" of their dogma and as such must be destroyed.
With Communism, Socialists look like the middle ground and embraced by Radical Capitalists as allies against the more radical Communists. Thus Socialist only were able to get into power more due to the fear of the success of the Communists. i.e Radical Capitalists embraced a lesser evil to destroy a greater evil.
The problem has been since the collapse of the Soviet Union (and some indication that this attack on Socialism started with the fall of Vietnam, for how it fell indicated that Soviet style Communism had passed its peak), there is no longer a viable Communist movement to fear, and thus the Radical Capitalist have decided to attack their other enemy the Socialists and other moderates.
Nothing "furrin" about breaking up concentrations of power to prevent the abuse and arbitrary usage of that power. It's downright American. 
No matter how you try, sooner or later you end up having to compromise. In the case of Communism, the need to control to make sure a new "Bourgeoisie" does not emerge become more and more clear. In the case of the Soviet Union under Stalin it was the bureaucrats that become the new "Bourgeoisie" (and the Kleptocrats that ran Russia under Yeltsin). Under the post-Mao China, the sons and daughters (and grandsons, Granddaughters and great... became the new "Bourgeoisie" . Thus the system was doomed from day one, for no one knew how to make sure one's own family did not become what one was fighting against.
As to Capitalists, the needs to "Public Places" became clear, you can NOT have Capitalism if you have to pay each time you crosses someone's property line (Thus Common Roads, ship-lines, canals survived any push to Capitalism, in fact were encouraged to be build to support the Capitalists). Some times these "Public Places" would be owned by private people, such as the Railroads, but the need to make sure these private people do NOT exploit their control over the "Public Place" quickly became clear and regulations were imposed on them to make sure other Capitalists can thrive.
Thus, even the most Capitalists of Countries adopt Communistic ways (For Example in the US, Government take care of the Roads, ports, Rivers, Canals, Airports etc. Railroads are "private" but subject to massive regulations by the US Department of Transportation).
Thus no one has developed a pure Capitalist system nor a pure Communistic system. Some sort of mixed system is preferred. Sometime the Mix has to change (The big push for Nationalization of the Railroads, big almost necessary in 1900, was no longer needed by 1950 as the Truck and Automobile ended the Railroad's monopoly in long range land transport), sometime it can last for Centuries (Except for brief time periods, Roads have been Government run). Sometime the operation is mixed (Sea Ports for example, often set up by Government, and who can use what part of the port is set by Government, but the actual loading, unloading and dock where both are done, done by private people). Airports are the other extreme, owned by the Government. as a community service, the Airport Terminal is run and operated by the Government (including getting bags off the plane), but any storage of the Planes and maintenance of the planes is done elsewhere by Private parties.
I bring this up, for most arguments between "Capitalists" and "Communists" tends to be how to divide up between the two extremes. Military operations are almost always "Communistic" (no one is heard "I died so that others may make money, and my wife and kids can die in poverty). On the other extreme, it is often better to do many a job by oneself as opposed to as a member of a group.
All Societies have just had to balance between the two extremes and sometimes change that mix and then change it back. The Classic example are Canals and Railroads. When both started both were Capitalist, run by individuals. Soon after it was found that these were extremely important for the overall economy and the Government stepped in (Building the Erie and Pennsylvania Canals for example in the 1820s and 1830s). The profit margin was so high, especially in regards to the Railroads tied in with the Canals, that Capitalist then stepped in to build more railroads and the Government pulled out of building Railroads (1859 Pennsylvania sold its Portage Railway to the Pennsylvania Railroad for example, it was hard for the Government to decide where the Railroad should go, so it was left to private companies to decided where they could make money). The problem was by 1900, most of the US was served by Railroads, who had dropped the price of transportation down to below the cost of any other means of transport. On the hand, the rates produced excessive profits for the Railroad for they tended to have de facto monopolies, thus the big push to take them over around 1900 (and many a community encouraged competition by encouraging the early Interurban Streetcar system, a system that could be built cheaply and thus provide competition to the steam locomotive lines).
In response to the above push to nationalization, the US adopted heavy regulations of the Railroad. In effect making the Railroad almost the same as the Government, but privately owned, but responsible to the voters more then they stockholders. This was acceptable for the profits of these railroads were excessive and this continued till the 1960s.
Come the 1920s, Trucks operating on paved roads, started to compete with the Railroads. These first put out of business the electric interurbans, for unlike the interurbans the trucking companies did not have to maintain they right of way (paving was done by the States often with gasoline taxes, collected from cars and trucks, but the cars doing minimal wear and tear on the roads compared to the Trucks). This advantage was made national with the paving of US 30 in 1926 from the Atlantic to the Pacific (Followed over the next 20 years with additional paving of what had been up to that time dirt roads). Thus by the end of WWII, Trains were no longer the monopoly they had been. The push to nationalized the Railroads died. Regulation was weaken due to fears it would bankrupt the rail lines given the new competition of Trucks. Thus you entered the post WWII decline of the Railroads that by the 1960s ended most regulations when it came to what to charge on shipments by rail. This decline lead to Nationalization in the from of Conrail, which, if had not been for the oil crisis of the 1970s, expanded to the rest of the US Railroad industry (This nationalization was due to the need to provide Rail as a "Public Place" to users of rail as a "Public Place" more then the needs of the actual rail lines themselves). By the 1980s, the need to nationalized had again disappeared as the need to ship containers by rail (due to high oil prices) AND the need to ship Coal by Rail (as an alternative to oil) made trains once again profitable not only to the people using it, but to the railroads themselves.
Yes, what makes Trains profitable today are Container and Coal Shipments. Grain is mostly shipped by Barge down the Mississippi (Through some is shipped by Rail to the nearest barge port). Fuel come up the Mississippi by barge, not rail for barge is cheaper. Rail's "Niche" is connecting the West Coast with the Mississippi River System (including the Missouri, Red and Ohio Rivers) and then to the East Coast. At the present time, no need to Nationalized it, but note, it was Government owned in the 1830s, for all practical purposes from the 1880s till 1950 given the ICC control over the rail-lines, again in the 1970s with Conrail. I know the Pennsylvania Canal and Conrail did NOT go outside the Northeast (and the canal only in Pennsylvania and the Railroad tied in with the PA Canal only over Allegheny Mountain) but it shows you how much the Community in the from of Government was involved with the Railroad. I bring up the railroad to show how Community Control of the "Public Place" like a Railroad can come and go depending on what is happening within a society. All of the above situation was a "mixed" Economic System, but what was "Communistic" and what was "Capitalist" varied with time and changes in society. That is something we must remember when we discuss what should community controlled (Communists) and what should be left up to individuals (Capitalists), things change.
