Why does Trump do better with Republicans that live in less white areas?

[Ljube]

So, prejudice/racism is the answer? I thought that was more of a left wing smear than a legitimate answer, but I guess not.

I'd say both sides get more homogenized. You have uniformity in voting of both minorities and whites in mixed areas. I think it's just a normal consequence of two different groups of people living together and the majority group believing they are under siege by the minority group (Homogenization of minority groups is normal and expected).