This isn't exclusive to biography. In the UK, British imperial history, very much histories of racial slavery, is dominated by white historians. They are rallying up publishing contracts to write about our ancestors too... lots of those books are voyeuristic AF πππ³π³
Why do white male authors overwhelmingly get the opportunity to write biographies of Black icons? There is one coming out penned by a 46-year-old on an icon dating back to the 1940s. The same opportunities aren't extended for Black writers and white icons.