M.W.
I think the key in your question is ‘white culture at large.’ What is ‘white culture?’ There is Italian culture, English culture, Greek culture, etc., but I don’t think there really is a ‘white culture.’ One can define ‘black’ (African-American) culture simply because there’s no way to separate African-Americans by their ancestors’ ethnic groups; I’m sure many don’t know what part of Africa their ancestors came from. So while ‘white’ is not one culture, ‘black’ is, at least in the United States. Regarding the title of the book, I bet they picked it because the question is something most people have never heard. It attracts attention, yet is so absurd it won’t offend most people. If the title brought up a more well-known stereotype, like ‘Why do black people steal so much,’ it would be far more offensive, and for good reason.