Snitches get stitches. At one time, one of the local black leaders complained about police being slow to respond in cases like this. The police chief rebutted the claim basically by saying that speed wasn't necessary because witnesses refused to help investigators.
Consequences. Learn to live with constant murder if you refuse to cooperate with police. I don't see the Nation of Islam or the New Black Panthers opening up alternate Police centers. They seem just fine with black on black crime, and they likely will not snitch either.
This has been going on for years, and no one seems to learn the lesson...or if they do, they move out.