Why I'm not happy with the AP's decision to support capitalizing "black."

[Emrys]

11. I copy-edit a lot of non-fiction books, both for UK and US publishers.

I can't think of a publisher I've worked with for quite a few years that has had a hard-and-fast rule about this issue (and many others).

We generally follow the author's preferences (more and more publishers do this nowadays rather than having a rigid house style, the main aims being consistency and minimizing the need for editorial changes), which may have ideological reasons behind them, and make sure the usages are consistent. Similarly with white, though there's a logical argument that if one term has an initial cap, the other would too.