It's apparent you've never been under duress in any time of environment while a crime is taking place. Do you really think a robber who just pulled his gun isn't going to be nervous? Some punk kid trying to rob a gas station isn't going to have the accuracy and knowledge to handle his weapon for some sort of miraculous 'head shot' while someone who's trained and/or been in that type of situation WILL be able to pull off a duck, cover and draw his weapon.
You should really start thinking things through before you post, because you're basing your arguements on 'what ifs'.
I've had a gun pulled at one of the places I've worked at while I was there, and let me tell you. The guy with the gun was just as freaked out about doing it as I was about having it done.
Having said that, if you believe that (lets just example this) Grace is going to the store, and a guy pulls a gun while looking right at her. Do you really believe she's just going to whip out her gun right then and there while he's pointing at her? Because that's the situation I see you imagining taking place.