I haven't worn a badge for going on 17 years. In all honesty, in the 3 agencies I worked for in the metro area, I never saw any hint of corruption in any officer I worked with. Never. Despite what people think, when a cop does something wrong his fellow cops are almost always his worst enemy. I saw plenty of officers abuse their authority on occasion but never in a physical way. I was even guilty of it. A guy copped an attitude with me one night and instead of getting a verbal warning I wrote him for something like 17 or 18 violations. And guess what? I got awakened late one morning several days later with a pissed off deputy DA on the other end of the phone that chewed my ass for about 10 mins. He dismissed everything because he knew I was being a bigger dick than the guy I stopped. Lesson learned.
You want massive change? Start with a look in the mirror. And that goes for the rest of society, too. Start taking some fucking personal responsibility for your actions and behavior (obviously "you" in a general sense...not directed at any individual).
You can start by not being an asshole when a cop stops you for going 15 mph over the speed limit and asking, "Don't you have anything better to do?". You can start by recognizing there is a very small number of "bad" cops. Very small. Most are very honorable people. Many are young and have a difficult job and it takes a while to grow into it and develop wisdom. You can start by recognizing that sometimes it's a dirty job and most "normal" people are oftentimes appalled at what it takes to get someone into custody. It can be ugly. You can start by recognizing guys like Chauvin represent an almost statistically insignificant number of officers. But they become massively significant in an incident like the unnecessary death of a citizen. But the numbers of bad cops are still very small...and they just got smaller when these 4 asshats were fired. You can start by recognizing that cops all over the country are cussing those SoBs for what they're having to endure right now. You can start by not telling the officer that stopped you to talk with you because you're driving like Stevie Wonder the only reason he stopped you is because you're black...or pick a bullshit reason other than that. Cops are not societies whipping boys. Cops don't have to put up with your bullshit...but most do.
Take some fucking personal responsibility for your actions. Teach your kids to do the same.
I've got news for you. This massive change you want really needs to occur within society more than most police departments. That in no way is meant to say there aren't a few bad cops and maybe even a few bad departments. There are. But, in my opinion, the bigger problem is society in general.