I've talked to a lot of cops about this kind of thing, and here are some observations.
1. Around 600,000 men are released from US prisons every year, and around 250,000 are black.
2. I think -- I can't prove this -- that from long observation of the police, perhaps 20% shouldn't be on the street because of problems of authoritarianism, racism, burnout, poor training, stupidity and other issues. There are about 800,000 cops in the US, which means you could have 150,000 really bad cops out there. When these two populations interact, you're going to have tragedies. It's absolutely inevitable. Trying to stop these things is like trying to stop traffic deaths. If you have cars, people are going to die in them. If you have hundreds of thousands of felons released from prisons every year, and all those bad cops, you're going to get really bad killings.
3. Fixing it would be enormously expensive. Enormously expensive. Billions and billions of more dollars, on top of what is already spent, and it probably still wouldn't fix it.
4. The US is awash with guns. Cops, like anyone else, get scared, and they get pissed off, and they over-react. With so many guns, and so many violent people out there, when somebody resists a cop, they don't really spend time thinking about what they should do. They simply put the violator on the ground, black, white, male, female, they don't care. So, you get dead people. Get used to it.
5. I really don't think racism is a big motive (although it is in some cases.) Usually, I think, it's bad training, I think it's carelessness and anger and exasperation.
6. A lot of cops will tell you that if you took 80% of the murderers out of prison, and replaced them with all the ratshit criminals, black, white and other, running around in the streets, you'd have quite a peaceful civilization. Most murderers won't kill a second time. A lot of these guys who are the center of the Black Lives Matter attention are simply assholes -- passing bad counterfeit bills that rip off the local grocer, shoplifting stuff and resisting when the cops are called, and so on. These guys drive the cops crazy, and sometimes they get whacked around when they shouldn't.