In fairness, it must be scary to be a cop in a restless US neigborhood. You never know when you'll get a split second's notice that somebody is opening fire. Shoot first and ask questions later used to be satire but in 2015 it may be the best route for a cop who wants to make it home to see their kid rather than attending their own emotional funeral in a box while the kid salutes the dead hero.
Sure I'd hate it if my relative were the victim of the mistake- but if there are guns all over the place and people aren't ready to try to push that genie back into the bottle, there's going to be a balance between cops being killed and public being killed that has to favor the cops or it would be even crazier to be a cop than it already is.
Just for clarity, there are lots of places in the First World where the cops are not armed and/or don't need to be. Including in the US. But you'll never hear about those in the MSM that caters for prurient interest in conflict and drama and sees no foul in helping to provoke a riot.