You're taking it off in many different directions. I'm approaching one point: police should apply only the amount of force necessary.
In particular, (1) no violence toward non-violent offenders, (2) don't hire cops who are in it for the power or to push people around, and (3) hold them accountable for misbehavior.
The point of a police officer isn't to enforce the law. It's to identify lawbreakers and either deal with small infractions with a citation, or arrest the offender and bring them into the criminal justice system.
Why is this cultural? Race, creed and color don't matter - or shouldn't. The law isn't about cultural norms.
Does community policing work better? It makes sense it would. So hire officers from the various communities.
Nobody has to be perfect. We just have to be better.