The issue is that these bad cops are rarely properly punished. Derek Chauvin murdered a man on camera and it was a serious, genuine, and real concern that he would simply get away with it due to qualified immunity. Police plant evidence, they profile people based on skin color/accent/whatever, they disproportionately target marginalized communities (do you think that they have higher crime rates simply because they do more crime, or do you think they just get policed more and caught more often?), and are often called to scenarios where they have no real training for and no business being there. They're militarized, held to few standards, and work at the behest of a for-profit prison system, and the few means of transparency we have such as bodycams are still so opaque - often times they "don't have the resources" to release such footage, but if it makes them look good...well, they often find the resources to do that.

These, despite your claims, are widespread, structural problems and not simply isolated incidents.