Sucks to have to point it out, but a lot of the problem really is militarization. Perhaps half of active police are former military, very often veterans. And the other half are trained by what are usually former military, very often veterans. Police training has become very militaristic. Cops are routinely trained to empty their magazines and make sure. They are taught to shoot to kill. Because Hollywood isn't real life, and shooting to wound isn't often possible, this does make center of mass make a degree of sense. But back in the day they were issued six-round revolvers and taught to fire a couple shots and then make further decisions. Takes longer to reload a revolver, and fewer shots are available. So more fire discipline is warranted. Modern police are issues semi-automatic pistols that can hold up to 18+1. And they are taught to keep firing to prevent the assailant from having the opportunity to return fire. They can easily fire half a dozen rounds before the target even hits the ground.
The skills and training that make good military are completely incompatible with the skills and training that result in good cops. Military and police have entirely different skillsets and functions.
Pains me to say it, but prior military service should disqualify someone from serving as a police officer. And prior military service should absolutely disqualify someone from training police officers.