Criminals also know murder adds to the prosecution and manhunt. Most only hand over a note. Introducing gunplay seems a step back. They will get caught anyway.I know the mortality rate is MUCH higher for the unarmed person in a gunfight than the one that is armed. I also know I don't want to depend on the mercies of an armed individual with the intention of robbing a bank at gunpoint, to not harm anyone. "PLEASE don't shoot me" is a poor defensive tactic.
I bet the average criminal would be a lot less likely to try to rob if he thought EVERYONE in the bank was armed.
Not trying to be argumentative or Johnny Bravo here. I'm just saying a criminal ALWAYS wants to have the advantage when it comes to imposing their will. When you even the odds or stack them against him, AND HE KNOWS IT, the probabilities go way down.