A friend of a friend is a long-term Chicago police officer. His take on the problem of police shootings is that veterans from the wars in Afghanistan and Iraq have a different mindset than the vets of Vietnam and Korea had in the old days.
He rides in patrol cars with the new guys. He says that they think that they are patrolling occupied territory. He tells them, "No. These are citizens. Some of tehm are bad guys, but all of them are the people whom we are serving and protecting."
He says that guys of his generation came back with experience, or at least the mindset of, hand-to-hand combat. They'd see a guy on the street with a knife, and they'd get out their night sticks. He says the new guys get out their guns.
Now, the history of police shooting in chicago 30 years ago was not paradise. I don't know how much credence can be put on this guy's ideas. But I thought they were worth reporting.