> Also, Paris for whatever reason seems to have way fewer visible problems with homelessness than SF. It's possible they are just keeping it away from the public eye though.

While France isn't above trying to hide poverty, it's still not as prevalent an attitude as it is in Britain and the US.

I think the answer's pretty simple : the welfare and healthcare system is just better. It's harder to be homeless and addicted in France than the US. SF in particular seems to have a drug problem.