You don't ask easy questions, do you. Look, I have been out of the NYPD for forty some years, and out of the rest of it for five or ten. Behind me nothing has changed that I can see. But I would say what I have always said: cops must be taught. And the bosses must go down in the street with them to see what they are doing. Half the 40,000 different police departments in the country get almost no training at all. None of the police academies that I know about teach common good manners to the mostly blue collar types who become cops. Doing so would be a start. Watching what they do from up close would be a start also.
Weed out the obvious tough guys and racists. This also is not being done.
A few more college guys as cops would help too.
All these suggestions are old now. I made most of them myself long long ago, at a time when there was a chance my voice would be listened to. They have never been implemented. Your next question should be, why not?
Sorry, but this is the best I can do for now.