To me, much of the root cause (it's not just black males per se; think of all the dogs shot mostly unnecessarily by police for instance -- https://puppycidedb.com/) is the over-aggressive militarization of the American police force. Which occurred for many reasons, but primarily was due to various moral panics such as the "war on drugs", and the need of our oversized military industry to dispose of excess military equipment. (See Balko's book on this: https://www.amazon.com/Rise-Warrior-Cop-Militarization-Ameri...)
Ultimately, the problem I can see with such policies is that the "war" paradigms too many police departments are obsessed with divide people between The Good Guys and The Enemy. The police force should be about community first (protect and serve etc.). But when the motif is more Good Guys vs. The Enemy, this probably does allow things like racial bias to play an oversized role. And when the motif is more War War War, it probably encourages hair-trigger responses.
In my opinion, American police violence (and we do IMHO have the most over-aggressive culture of any rich world nation I've seen) won't be fixed until this attitude changes. This is less a police officer issue (officers can be trained to any culture) and more of the type of culture encouraged at a legislative level.
