There is more to this than just training. Imagine being a cop in the US. Every single person you encounter might have a gun since it's their constitutional right to own one. The probability rises if the person you encounter is a criminal suspect. Of course they gonna drill a "shoot first, ask later" mentality into you.
That's obviously no excuse for police to use force in situations they have full control over. These are all just symptoms of a system that is through and through fucked up and that needs a major rework.

Okay first of all, even if that's comparable, why the FUCK should we be in the same ballpark as mexico's police fatalities? Canada is even bigger if we're really talking about landmass, and it shouldn't be normalized to kill so many people regardless of where we are or how big we are.