Police are trained that it is an "us or them" situation every time they encounter someone. Everyone will try to kill you unless proven otherwise.
They are taught if someone has a knife pulled they will be able to kill them.
Now obviously a severely disabled teen would not be able to rush them before they pulled their weapons. But they are not taught to evaluate or deescalate these situations. They are taught to kill
Unfortunately I don't think that would be practical in the US. We do have many people with guns and weapons in general. An overhaul of training and giving access to appropriate tools would be most important. As it stands US cops are taught that a gun is their best tool and that's how they use it. Maybe enforce pairs where only the senior most trained officer has a gun?
Otherwise I would like to see a lot more unarmed units focused on community policing issues. Whether that be a part of the police force or not. I also agree with units that only do traffic enforcement nothing more. That alone would reduce cop shootings massively. Many departments treat traffic stops as a way to catch other crimes and could care less about enforcing traffic laws that keep us safe