What often happens is that if there is sufficient negative attention, the officer will be placed on paid leave pending an administrative review. Then after the public moves on to something else, the administrative review finds that the officer did nothing wrong and that it was the unarmed victim's fault for being shot.

At worst the officers will get a paid vacation then will be back to work after the police investigate if the police did anything wrong.

Yeah, they do it by giving the Swat team medals for valour

The UK has a national(+) police complaints commission which would automatically investigate fatal shootings. The US does not.

(+) in practice, a different one for each of the four nations