Yeaaahhh... amazingly enough, having a gun on you, even a stolen one, even after a cop's told you to drop it, isn't actually a capital offense in the US, particularly not one that bypasses that whole due process and appeals and whatnot thing and goes straight to the execution. If you start shooting or brandishing, maybe, but we currently have no indication of that, so far as I can tell.
Cop's job isn't extrajudicial killing. The job can involve it, and it's an important tool, but generally speaking discouraging that is a good idea. Less riots, less dead people, more justice and law and all that tomfoolery. Good stuff, mostly. Maybe some more dead cops, too, but endangering their life for that whole legal process thing is kinda' literally what they signed up for.
... all that said, it looks like some of the rioting may be calming down (let's hope neither the police nor others antagonize back into full swing), which is generally a good thing. Anyone know how unsurprising this all is? Haven't exactly been paying attention to the state of police behavior in a city in wisconsin... even if it is milwaukee.
And nah, not every shooting. But it's happened enough (among other things, like the person shot being armed but not actually drawing or attempting to) just trusting it was a good shoot when the police say the person was armed is... probably not the best of ideas.
E: And to the edit, the shitty attitude is immediately defaulting to the cops being right to kill this guy, even without any sort of evidence besides "police said was armed and at-least-previously criminal". That is, in part, exactly the attitude that's led to BLM, or at least some similar, to frankly kinda' be needed.