The point of ACAB is to claim that ALL police are bastards because they all allow some to be as bad as they are. Everyone is aware there are good people.

They are in a position of power and thus should be capable using that power for self governance. Except, they don't. How often does a cop blatantly break the law and murder a civilian with no repercussions? If they are going to investigate themselves and find no wrongdoing and never improve, then ACAB.

You have a fundamental misunderstanding.

The philosophy behind ACAB is that the American police system and its proponents abuse the system and work to keep each other from facing consequences. "Good cops" may enter the force, but they don't last long, because those who don't play along and look the other way eventually get ousted, whereas those they tattled on get rehired at a different station.

The idea isn't that literally all cops ever will always be bastards. It's that (under the current system) all cops are bastards.

Hey Dick, can I call you Dick? So, Dick, the problem people have with the police is summed up like this: We are tired of the jackboots not being accountable for their crimes against humanity.

That clear enough for you Dick?

Police actions are the sole reason for the loss of trust. It's accelerated recently because we've all got what would once have been a godlike camera in our pockets now and the means to share those videos globally.

Don't worry, Trump will get around to fucking that up too.