> What does cultural homogeneity have anything to do with the way a country treats its homeless?

It's easier to be generous to people who are more like oneself, and who are physically closer to oneself.

Consider all the people in Europe right now who may be perfectly happy to support generous welfare for homeless people who happen to have been born on the same side of their borders, but who are hostile to homeless people who just fled Syria.

Or consider the difficulty of scrapping every national welfare system in Europe and uniting them under a single EU government. I contend that would be very difficult. America is more like the EU than it is like Norway. Norway is much more like Massachusetts, which has very Norway-like quality-of-life metrics.