They are always trying to assert an authority which doesn't need to be invoked, except in extremis.
The big issue is how to humanise their standard operating procedures in a second amendment nation.
These things are connected. If the public is armed, policing is likely to be harsh.
That is the first step.
The second step is to try and understand the relationship between the police and black people. And to find ways to improve it. That is a conversation that needs to happen everywhere.
There are problems here too. But the ingredients are different. Few bobbies are armed with guns. Few black people are armed with guns. We don't have a large population of people whose ancestors were black English slaves (not that we are innocent in the wide world, but domestic slavery was small scale and was ruled out in the eighteenth century). I believe British black people are mostly second or third generation immigrants, some from colonial slave descent. Importantly, they or an ancestor chose to come here. So maybe there's less cause or justification for ancestral rage.
So I don't see that our problems are all due to policing. Many are due to poverty. Some may be cultural. I should think those things are in the mix in the USA too. I'd be very careful of a set of ideas which simply says all police are wicked and all black people are victims. Too black and white. Although clearly that is more often true than i have previously realised.