Why black (to describe race) and not Black? Poynter discusses.
This includes discussions with Norm Goldstein, editor of the AP stylebook, and John McIntyre, president of ACES and desk chief at the Baltimore Sun.
"Newspapers ... don't impose language, they follow the language," McIntyre said. "The terms 'black' and 'white' with lowercase have a long history," he said, noting it's not a wise idea to veer away from what readers use. "It's very difficult to alter traditional uses. It's been 20 years we've been encouraged to use 'African American' instead of 'black.' And it's still not a settled usage."The author, Aly Colón, notes one of the difficulties newspapers face in changing style.
However, what I understood by talking to both Goldstein and McIntyre is that many publications use AP style and AP determines its style by watching what other publications do. I see the possibility of circular thinking that may make change difficult.