I think it offends their liberal racism to show black male/white female. After all the white male/black female combination has existed since plantation days and later the white men enjoying the mixed race prostitutes in New Orleans and elsewhere.
Well, the white on black rape number is so low it is listed as * the FBI crime stats. It is next to nonexistent.
Now, marriage/dating isn’t rape, but that does show there isn’t much demand for it.