OP was talking about THE STORE being robbed, not the patrons of the store. I've watched dozens of videos on YouTube of armed robberies and none showed the robber attempting to rob the customers but rather the store, even if I was asked to give up my wallet that's what I would do, it's just a wallet. In many of these videos, shootouts usually begin with John Q Public drawing on the robber, some of the videos show same shooting at the robber as he is leaving. This is the scenario I was addressing. Body language of the robber, who many times has his BACK to the patrons means for the most part that he's getting cash and leaving, neither the post or my reply was responding to some other WHAT-IF scenario.
What if he turns his gun on the patrons? What if he and his partner start herding customers to the cooler? What if he is mad as heck and and making threatening gestures and talk in general? These are certainly different scenarios that I wasn't addressing.
Certainly there are Good Samaritan laws in place but once again, you will have to prove that you were in fear of your life. Either the DA or the Defense will grill you extensively, what if video evidence proves he had his back to you the whole time and wasn't paying you the slightest attention? If you have never faced a police interrogation or prosecuted on the witness stand I would advise not to be hasty to get involved. If you can't read body language or if you have no law enforcement background and you aren't the stores security why put yourself in the position that George Zimmerman did?
Having said that, I always take into account that the store I'm in will be robbed and this brings me to my mindset. I'm no longer paid to protect people and when I was, only another LEO understands the tsunami of paperwork, testimonies, criticism, vilification and second guessing that goes on long after, and I mean long after the incident. This is the real world. What if race becomes an issue and Rev. Al and Rev. Jessie get involved? Now this issue isn't going away. What if the perp looks 20 but is really 15? What if his parents are high rollers like in the Mike Nyfong case (not that he was right and I'm glad he was fired). This is a Pandora box and the media and all the self righteous warriors are going to start digging up as much dirt on you as they can all the way to making it up, allegations are enough today.
What if your shooting was off or is spun to make you look like Zimmerman, a racist blood thirsty, wannabe cop?
So my mindset is simple which is why I also carry simple tools, a J frame in my front pocket which means I am concealed and have an advantage plus drawing from the pocket can seem innocent as if I was pulling out a wallet. It also means my hand can be ready to draw but I don't have to and if wrong I can't be accused of brandishing because my hand never left my pocket. The distances we are talking about is more a point-to-shoot scenario and not a take a nice slow aimed shot with your brand new $150 sights, in fact most of these shootings occur under tremendous stress, tunnel vision (which means peripheral eyesight gets blurred and even the rear site disappears. Ever wonder why in many shootings cops expend so many rounds? It has to do with blurred sight coupled with adrenaline that somehow makes intricate dexterity difficult, it muffles your hearing, your breathing is labored, your heart is pumping, and it disconnects you from everything but the task at hand which is why many cops are surprised that they fired a whole magazine when they testify that they only shot once or twice.
My J frame is for IF the scenario goes from robbery to homicide and usually this means someone already got shot, that's my clearest proof and my get-out-of-jail-free card. Sounds callous, welcome to the real world.