Why do people put R&B under urban contemporary and not adult contemporary?

When it comes to Celine Dion and Elton John music, hell even some Miley Cyrus slow songs, they put them under ADULT CONTEMPORARY. But when it's slow music by African Americans, like R&B (sung by Mariah Carey, Ashanti, Toni Braxton, etc), the racist radio people put it under URBAN contemporary. Honey, R&B music is more adult than music for street people. Hip hop/rap is URBAN, not R&B.