I STRONGLY disagree with that. My son attends an 'inner city' magnet school in Tampa (and my oldest graduated from there a few years ago). The school is about 3/4 black (local kids) and 1/4 magnet (predominately white). I know many of the teachers there (both magnet and traditional). almost ALL of them work hard to TRY and teach the kids (there are a few who do as little as possible, but the principal is working hard to eliminate them).
The problem is LACK OF FAMILY AND VALUES. Those kids do not see the value in an education. Most come from single parent homes and were not taught the basic values (respect, honesty, etc).
Having taught hs for several years, I can tell you - you cannot teach someone who doesn't want to learn!