I don’t think it’s just a US thing. Even in places with more limited free speech, people can get away with saying ignorant and heinous things as long as it is technically within the letter of the law, or if the law is not strictly enforced.

It’s against the law in China to threaten violence or use hate speech, for example, but in practice, I think the law may as well be reworded to clarify that such language is only really illegal when aimed at Han Chinese people.

Not enough countries care about protecting anyone other than their primary in-group.