Its because black and white are colors, words that have uses outside specific proper nouns and a lot of people even use them as adjectives even in the racial sense. So until very recently they'd never be caught by spellcheck. Latino is a specific label that is only used in the "proper noun" sense, so it likely always has been.

So in this case, they capitalized black and then didn't do so for white. Regardless of if the went back to capitalized the B, or their spellcheck got all three and the went back to downsize the W, a choice was made and its anti-white.