And they never have the ability to shoot anyone who isn't actively killing people?
Police never have the AUTHORITY to shoot anyone who isn't actively attempting to kill people. That's the important issue here: authority, not "ability." Without authority, the use of force is criminal.
The second is simply false, because the authorities can shoot lots of people who aren't currently actively attacking anyone. You'll note that Federal troops...
Are you really too stupid to know the difference between police and the military?
Now we've got many fewer enemies, and the process for finding them is much more complicated because they don't all wear the same shirt, but that just means that there's a lot of internal process the Executive branch has to go through before OKing the target.
The government also has to abide by the Geneva Conventions. Either the target is an enemy soldier and the Geneva Conventions apply, or he is not a soldier and US criminal law (including the 5th Amendment) applies. There is no other category. Obama (and GW Bush before him) might have claimed there was, but both of them are war criminals.