Not that I'm arguing that America is racist, but I think you're confusing two different things here.

Homogeneous countries often (but not always) have a kind of cultural xenophobia. I've experienced that in China as you say, but found the complete opposite in countries like Vietnam and even South Korea.

But the racism at issue in America was legally enforced and as far as I know (with the exception of South Africa), unique in the modern world (Mugabe had a go at enforcing openly racist laws in Zimbabwe but not on nearly the same scale).

That's the difference between a racist country and a country that has racist people in it.

Of course, Jim Crow laws were struck down almost 60 years ago in the US, but 60 years isn't really that long. Many people alive today lived during segregation.

So I mean sure, there's a case to be made that this faurly recent history makes America a racist country, just as people might argue that South Africa is a racist country. I'm not taking a position one way or the other. Because the point is, who cares about this purely semantic debate when there are concrete issues to solve?