Nearly everyone cares. But the people you're referring to carefully weigh all the facts (what little there usually are) before coming to a conclusion.

In which trial was it unambiguous that the police broke the law and also demonstrated institutionalized racism, and faced no repercussions?

I'm all for police accountability, but when we do have video evidence it often ambiguous on if the officer was in the wrong in using force. And when it isn't ambiguous, the officer goes to jail.