For some reason, the solution to this (again, very genuine) problem “bad cops tend to get fired and travel to some other agency” is not “let’s fix the holes that make that pattern possible” but “See? Police agencies always protect bad cops! Let’s starve them for money and make them desperate for more people!
We had decades of uncritical support of police from most of the population until cameras started showing up everywhere to let us see what we were supporting. It turns out those decades of mostly uncritical support does not seem to have resulted in the sorts of police we want. So maybe try being upset about the shitty police instead of being upset about people being upset about the shitty police.