First, I really appreciate the way you are posing your thoughts and pushing the conversation. What you describe in the first part is very valid (and obviously I whole heartedly agree that something needs to be done).
My opinion, what you posit is exactly why we must require greater scrutiny for ARMED POSITION OF AUTHORITY. We give our officers weapons (sometimes military-grade weapons), and we give them a great amount of freedom in the way they use those weapons against civilians:
1) They know the way decades (centuries) have interpreted an officer's claim "I feared for their life." So whether a person has a knife or a bb gun or a squirt gun, or just their fists ... this totally subjective "feared for their life" analysis is has been a get-out-of-jail-free card. (Remember also, we live in a country where even current generations lived through a time where you could tell an all white jury that you feared for life and directly invoke the persons race, and that would serve as a good enough defense for your actions). In most states, this is not the same level of scrutiny a civilian would end up receiving in a criminal court proceeding.
2) They operate with full knowledge that their actions fall under qualified immunity. I just don't see how anyone can deny that that alters your psyche when you go into situations. They know they will face no civil court consequences, none!
So in criminal court, they know their actions will be judged with much greater leniency than a typical civilian. In civil court they know there will be absolutely no consequences.
We use "law and order" as a means of directing our civilians' actions. There are consequences that we apply to them when they do horrible things to others ... this is the element of "deterrence" sought in our criminal justice system (tbc, I'm giving a lot of deference to ideas of a system I have much stronger feelings about). The most renowned words in our Declaration are the right to "life, liberty, and the pursuit of happiness." Our justice system as means of deterrence is sometimes a threat to take away YOUR LIFE (capital punishment), and many times a threat to take away you LIBERTY (incarceration/right to vote/etc). And beyond that, civil court offers another level of deterrence with harsh economic penalties even when it doesn't meet a criminal court burden. That is an extreme level of deterrence that we use as a society.
If we could simply "trust" that everyone would operate under the same moral codes and desire to keep neighbors and all communities safe, we wouldn't need to resort to this level of deterrence.
But we are arming people in a Police Force, and allowing them to operate without the same level of deterrence in place. They will not face the same level of scrutiny when using force that harms or kills someone. So without that, we have to just "trust" that they will wield that power safely and with responsibility.
WHY, and I do get worked up about this, WHY SHOULD I TRUST A POLICE OFFICER more than I trust my own neighbors? As a society, we've decided the community can't be trusted and so we need this level of deterrence, but why should I trust officers so much so that they don't need this? None of us voted on those officers. Here in NY, for decades, we've not been given ANY transparency about their actions (all internal records are shielded completely from public).
And here's my main point, for many departments the extent of education and training required is a HSD and couple months at a "police academy." (tbf, some departments require more, but it's still not enough imo). I'm supposed to trust this cop though, to make split second decisions that involve someone's life. I'm supposed to trust this cop to have the mental fortitude to THINK about how he just thoroughly searched someone, knows them to be unarmed, knows that the taser gun cannot be fired any more ... I'm supposed to trust that they won't murder a now unarmed black man in that moment.
I have always thought, why do our officers not have the same degree of training and education (classroom and practice) as doctors and lawyers? Why do we not have a P.O.D. (police officer doctorate) that is required for any and every cop. We require doctors to go through INTENSE levels of training and MULTIPLE, CONTINUED examinations/board certification, why? Because they hold someone's life and safety in their hands. We require lawyers to go through an intense level of training and THE HARDEST EXAM I COULD HAVE EVERY IMAGINED, why? Because they hold someone's liberty in their hands, someone's finances, or fiduciary duties.
If a doctor was on an operating table, and there was a a lot going on, a lot that I could not as a civilian reasonably manage, and he got mixed up or reacted in a way that caused the death of a patient ... a general civilian's ability to perform under those circumstances is not relevant and not an excuse. He will be held liable (sometimes criminally and civilly) based on what is reasonable for someone of his training and experience. And we as a society have set that bar, the required training and experience, VERY HIGH.
You may have seen the memes comparing other countries (tbf, memes don't get to nuance and often aren't accurate). But generally, you look at places like Norway, Finland, Germany or others: they require three-year degrees and multiple certifications that take years. Police Officers are required to get a similar level of robust training and education that teachers, doctors, and lawyers are. I dislike educational elitism, and the lack of affordability of our education model; that in itself needs to be overhauled ... I don't care that you didn't go to undergrad and study English Lit or Economics, but some police academies (since they are run by state regulations only) are only 2 WEEKS long. I want to know my Police Officers are best and brightest, that they've gone through programs that introduced them to many diverse settings (in terms of peoples AND ideas AND experiences).