The problem with the USA is that everything is dysfunctional, so it’s extremely difficult (e.g. impossible) to fix any one problem. Obviously no sane country would have the US approach to civilian ownership of small arms. Obviously no sane country would hand over ex-military kit to police forces. And obviously no sane country would hire precisely the wrong psychological profile of people to become police officers, and then train them in precisely all the wrong ways.
But the USA, far from being “the greatest country on Earth” is actually a backward and highly dysfunctional nation (and I lived there for 27 years and traveled and worked extensively across 42 of the 50 States) and sadly there is little or nothing that can be done to change any of the many huge and intractable problems there, not least because so many people are so ignorant and so simple-minded that they don’t even realize there are so many major problems.
So thanks for writing and posting, and my heart goes out to all those who continue to suffer from the kind of absurd horror you have written about, and all those who will suffer in the days and weeks and months and years and decades ahead.