I talked to a police officer in Germany and he told me that police abuse happens even if they wear cameras. He said that those who wear cameras simply don't record their colleagues who are hitting people i.e. looking to another direction deliberately. And I'm sure that if you start to punish them based on those body cameras, you'll see that the police officers will give you biased footage.

Although I can imagine that police officers start to change their behaviour because they're watched (there are studies showing positive changes in behaviour due to surveillance), there must also be more education for the police officers in regards to baseline probabilities so that they realize that black and white people aren't different in behaviour, this could help them to realize that their intuition is not profound. I think helping them to understand cognitive biases is a good way to start a shift.

All of this requires that they aren't doing abuses deliberately, though.