I think in some ways, this is a result of our fondness for the second amendment rights and arms as well as accepting the police as a necessary force to keep the peace.
I'm not sure if there is an easy way to de-escalate things. We might start with police 'engagement' procedures standardized from a federal level --but there'd probably be pushback from the states.
I do have a quibble with _always_ presuming innocence. If you see someone in the act, then I think they can take action without such presumption.
One of the specially hard things for me to understand is the necessity to shoot at 'disturbed' people wielding knives. Yes, I know knives are deadly --however, knives don't travel very far, compared to firearms, why not back up, give them a safe distance and try to de-escalate before shooting at the 'lunge.' Again, I know most of those disturbed people do mean harm[1], but you can avoid their intended harm by giving them space.
[1] Some intending assisted but unintended suicide from the police.