I read it some month ago, I don't have any source right now, sorry.
I remember reading it and thinking it was pretty obvious. I didn't bother saving any link.
Just look at how most people act when police arrives. That's not only an American thing. Non violent crimes are still made by criminals and they don't respond very well to police presence.
That said, American police needs better funding and better training. They need to learn how to deescalate situations.