The other developed countries are pulling away from us in quality of life because they have democratically maintained
socialism as a significant part of their political cultures. Thus, there are at least two
competing narratives for prosperity that gives politicians a wider set of tools to promote healthier economies. Also, major conflicts of interest are tolerated far less in that kind of competitive environment.
In fact, most of the Left parties in prosperous countries like Japan, France, UK and even Canada to an extent have ACTUAL MEMBERSHIP in organizations such as this
http://www.socialistinternational.orgThis is politically impossible in the US. The Democrats will half-heartedly try to duplicate some of the
results of social-democratic political cultures (such as copying the idea of universal healthcare) but it is like picking an apple from an orchard, dropping it in the desert and epecting the seeds to produce healthy trees.
Liberalism alone
cannot make a sufficiently compelling case for socialized services. And over here, Democrats turn pale and run away when they are accused of being socialists.
My short answer is that these other countries retain their economic alternatives, whereas we have not. Today we are a one-system country; one ideology with two well-marketed brands.
If you cannot effectively communicate a class-conscious view of society and economics, then the actual social policies will not follow or they will wither. This is something the left in the US needs to work on in the serious way; just do not be surprised if the Democratic party tries to oblitterate those efforts as it has in the past.