It is a complex problem with many causes. Being realistic, your low level officers are going to be poorly paid and you can't expect to have bright people there. Bright people can find better employment elsewhere. So you have people who are not the brightest and who are given leeway. You catch a cop on a bad day and you are in trouble.Such ignorance is by design. The law enforcement industry is not actively seeking high IQ types, but desires those slightly less inquisitive and more likely to blindly follow directions without much thought to what is behind the directives.
Another problem is the paranoia level in America. I understand perfectly that it is not the same to face an unknown packet or device in Norway than in America than in Israel. The expectations as to what might happen are vastly different. You cannot isolate the guy who overreacted from the environment around him.
In my view a lot needs to be done to diminish tensions, create a more peaceful environment, at home and internationally.
Many Americans truly see themselves as being under attack from outside for no reason. Under president Bush II America decided to kick some ass in revenge and went and did so with much chest thumping. That ignited the mess we now have in the Middle East and the worst humanitarian crisis since WWII. America is the first to use violence when it suits them but to claim violence against America is never justified.
Really, we need to calm down and think a bit before rushing into violent, stupid "solutions" that just make matters worse.
My two cents.