The smallest in Europe, on average, in home space built since 2003 (this is a 2011 study) and tiny compared to the average in the US. Furniture tends to be smaller; not as massively overbuilt and the available space is designed to be utilized efficiently. People in homes tend to spend time in the same rooms at the same time, too. Extra space is a very American concept - just because we have it doesn't mean it's necessary.

As for smaller roads; yes, many of their roads are 'smaller' - they have smaller vehicles, overall. And comprehensive, efficient public transport that minimizes the need for a vehicle at all for many people. I spend a lot of time in the UK and rarely feel like I'm being cramped or don't have enough space (rush hour on the London tube is a different story, I'll grant, but nothing is perfect).



The largest square is the US; the smallest is the UK.
US: 2,300sf
Australia: 2,217sf
Denmark: 1,475sf
France: 1,216sf
Spain: 1,044sf
Ireland: 947sf
UK: 818sf

http://www.apartmenttherapy.com/average-home-sizes-around-the-151738