I certainly don’t want to oversimplify, but I think it has a lot to do with “rugged invididualism”. There’s such a sense in this country that we are in it alone, every man for himself, we’re solely responsible for our own success or failure, even our own life or death, etc. Somehow most other countries still seem to understand, at least more generally and broadly, that we’re all in this together and “no man is an island”.