Real easy reason.
Snitches get Stitches.
Plus, the media are very into promoting the narrative that rape is prevalent in college -- BUT NOT when black students are doing the raping.
Rape is exclusively a problem of straight, middle-class, white, males. Regardless of what crime statistics might say.
Years ago on the radio, there was a show where callers could discuss crimes committed against them. One guy called up and said that his co worker, a young black man, had recently been robbed at gunpoint by an acquaintance, who was also black. When the man asked his coworker what he was going to do about it, the black man said “I’m not going to put another brother in jail”.
There you have it.