I've been in so cal during three revamps of a couple large departments and they become MORE polluted sooner than later.
Technology is rapidly chipping away at that. Now that every single citizen has a video camera in their pocket. Along with the resulting lawsuits and taxpayer money being paid to those damaged by police abuse, uncovered by that technology.
Imagine watching old episodes of Hill Street Blues, and instead of the Sergeant at roll call saying "hey, let's be careful out there", he says "never forget every thing you do is being recorded by everyone". Im guessing that's what they're preaching now.
Corrupt police are a symptom of a greater evil and I'm sad that my grand kids are probably going to either be enslaved or have to fight the real war that ensues. But the question is why are the Feds pushing militarization of local law enforcement? Why are laws that enhance corruption not removed from the books (RICO)? The evil isn't in the sucker fish it's in the large predators. The sucker fish are merely the clarion call.
Corrupt people are a symptom of a greater evil - we may be saying the same thing. I doubt police work, inherently, attracts corrupt candidates. (Perhaps more in response to SF's point) Your typical candidate is young and naive, never been in any trouble/caught in any trouble. Eager to serve, without realizing what that means until it's too late. It's more of a learned behavior, particularly when LEO could, and still do get away with murder.
It's impossible to fully man/woman every police force in the Nation with those whom many now believe must be morally superior Super Cops, that get it right every time. That's a fairly mpossible task. Even if possible, those Cops are few and far between, and there will never be enough of them to go around.
It's not your average young person that can be given a uniform, badge, gun and (until the advent of smartphones) unquestioned veracity - and not have it affect their behavior negatively. Combine that with outdated training and training officers who were products of that training.
A 28 year old Cop with no education other than a high school diploma and a several month Academy, can pull over a US Supreme Court Justice . . . and be in complete power. It's a power most normal people would not handle perfectly all the time. And once you've learned that behavior and used that power, and gotten away with the occasional unrecorded civil rights violation here and there, for years . . . it's tough to transition to Super Cop status.
I recall Obama speaking out against the militarization of law enforcement awhile back when he decided it was politically convenient. But I suspect militarization had been done, in part, because of prior instances of local law enforcement being sorely outgunned by highly militarized bad guys.
And perhaps because of government budgeting. Use all of the money by the end of the fiscal year, or get less money next year, which would look horrible in your evals. You can get everyone on the force their 5th set of Hi-Techs, flashlights, Glock, high powered binoculars, camera, etc. Or an Assault Vehicle.
Edit: Damn, that's too much to read. More importantly, I'm drinking cheap Chardonnay.