You speak as if the system is broken and in some ways I'm sure it is.
The legal system period could stand some improvements, but in the situation you posted the link to, there's a legit reason the guy was shot, it's not lack of training, it's just how the situation played out.
I remember a few years ago where a mentally handicapped boy was shot in his yard because he had a toy gun that looked very real. The cops thought it was real, and when you saw it, you'd think that too. It wasn't pink plastic, it was black and looked real.
Would you say more training would have prevented that?
Sometimes things aren't "right" or "wrong", they just are.
PS. The details may be wrong on the shooting, it's been a few years. Just in case they are wrong.
But it happens, that's the main point.
Honestly, I think it is broken. But it's not only the US System. It's everywhere. Greece, Germany, France... anywhere you turn and look, the systems seem to be broken.
However, I don't want to make this too political.
Speaking from experience, I used to sit in a wheelchair for a year because of my right leg. People that have seen me personally may have noticed a slight limp, sometimes even a moderate limp. It doesn't impair me, I can do what i have to do and even do SAR, however, the limp is there and that accident is the reason why I'm not a Cop or in the Military.
Anyhow, I know what it is like to sit in a wheelchair and depending what type of wheel chair you have, if you are an athlete or not.
Anyhow, that guy had one arm and one leg. He was waving with a metal object which turned out to be a pen. How hard can it possibly be to overturn and restrain a double amputee with one leg and one arm. This doesn't go towards you but "Give me a break!"
I know, I could have easily been overturned and restrained, no need to shoot, just knock that darn wheelchair over but don't shoot!
Anyhow, since I don't want this to turn political, I'll leave it at that. I just wanted to make a point that I believe that there is a much bigger issue at hand than just "Cops shooting dogs".