You're assuming they want the violence to stop. They don't. They benefit from it politically.
They need some way to motivate blacks to go out and vote for a rich, white, corporatist lesbian with whom they have absolutely nothing in common. The "cops are racist and Republicans back THEM" meme serves that end.
I’m assuming some governors, police headquarters, families, just people.. would come to the place where enough is enough.. and say to hell with being called names, and do something about this anarchy/terrorist in our own country. To sit and watch isn’t working... Police should go on strike... but it seems the people are sitting ducks and seemingly cooperating by doing nothing.