It's not the weapons the officers have to use. It's all about how to deescalate a situation which is really really hard. There are times when the first shot NEEDS to be lethal. But the challenge is determining in a split second if lethal force is required or not. For instance tasers. If a suspect has a handgun and the officer pulls their taser. The suspect pulls his weapon. The officer is now out gunned (taser in hand firearm likely still holstered) and in big trouble. As long as their are bad guys out there that are willing to fight to the death, and the officers do not know if the person they are facing has such a person cops will use lethal force.
As an aside we bought our first weapons when we lived in Oakland. We took lessons at a range where the OPD would train. The Range Master said they were some of the worst shots. I guess when you're trained to unload your clip on a suspect accuracy is not important.