The problem with law enforcement in America is the change in thought process that comes from the change in classification from peace officer to enforcement officer. They are no longer there to maintain peace. They are there to enforce the law as they see it and bend you to their will. They are kitted out like soldiers now. This causes them to take on the mindset of a soldier on patrol.
I saw and experienced this same transformation when I was in the military. When I was in the Navy standing guard even in war was typically a relaxed condition. You had a pistol and you patrolled the ship, pier and/or base, you remained alert for trouble, but you did not go looking for trouble and when you found it you tried to maintain order and diffuse the situation. Escalation and being a jerk were the last resort.
On the other hand, In Desert Storm when I was assigned to ride shotgun and guard the ships bus and my shipmates as it traveled through potentially hostile territory I was different guy. I wore 2nd Chance ceramic plate armor, a Kevlar helmet, carried extra ammo, a combat knife, gloves, etc. My head was on a swivel, I was in tactical mode, and I was constantly looking for trouble to arrive at any second. I was the only defense my buddies had.
This is what is happening to our police forces today. They are in tactical mode all the time. They simply do not know how to turn it off anymore. They will shoot first and ask questions later and since it is other police officers investigating the shooting they know they will suffer no repercussions if they kill someone because the fraternity protects its own.