If you go Brasil you'll see much more mingling and mixing.

The US is truly not a good barometer of that kind of integration.

The UK culture was never the best at integrating, like for example the Portuguese culture in Brasil. The Portuguese culture (Catholics) was much more lax with the race separation and thus you have more mixing. The British was more about separating, creating reserves, spots of this and that, etc.

The US is not the world, just because something happens somewhere doesn't mean that's a set truth. And the same everywhere.

White only racist culture will also fail because individuals will put superflous things above the meaningful things. And that always results in failure.

Culture and philosophy above everything else. Content of character is the value.