Not only a random thought but a bit strange at that! Just what are you saying here - that robbers should not have to face anyone who might protect themselves? All in all, a really strange response for this thread. Even Jesus used a whip which was fairly potent at the time...today requires a bit more...
Oh no, they should!
however, if you pull up on a guy running down the road.. Are you going to just take his word that the guy he chasing is what he says he is?
I sure as hell would not shoot him based on someones word.