I mean isn't there also substantial evidence (aka billions of interactions with a very low percentage of brutality when compared to said actions) that would disagree with it being a prominent issue? Also hasn't it also gone down over the years? Not entirely sure but I read somewhere showing like 85% of the time when a cop is fired/charged it's because another officer filed a report against them with evidence. You simply just don't see coverage on those cases. Where I'm from we had 2 officers fired due to the rest of the department finding out and immediately taking action. Cops don't like or protect dirty cops 90% of the time they just wait and file a report anonymously from the public so they won't get fired for publicly thrashing the other officer.