Did you ever watch The Sopranos? Tony seemed like a pretty decent family guy and tough-but-fair boss. Right up until you watched him beat someone to death.
When police carry a gun, they are brandishing the means to kill you. When they carry a badge, they are declaring they can do it with immunity. When they wear body armor, they're pointing out that they can't be hurt by your own gun. And when they wear the uniform, they proclaim that if you do try to resist their aggression, they will call hundreds or even thousands of their gang members to ensure you never see another sunrise.
So when you say "...sad because the cops who were shot weren't the ones guilty of the most recent high profile cases of police brutality" I think you're forgetting that the badge and the uniform proclaim them as members of the same tribe who intent to inflict harm on the innocent just as readily as their comrades who actually did.
They are a threat of violence by their nature and practice.
Now, whether they all understand that is a different matter. Sadly, they largely don't.