Fron DailyKos:

dailykos.com

The basic thesis is that because the US got rid of its actual leftist political parties in the various red scares and purges of the 20th century, there is a natural tendency for the US to drift right politically.

This is plausible, since the dominant voices out there are moderates prone to compromise, and an intransigent and radicalizing right.

This may be the best simple answer to “Why can’t the US have the nice things they have in Europe” that I’ve seen.