Well, first of all, those people who say that if the robber was going to shoot you, he would have already done it don't know much about REAL armed robberies.....grave yards are filled with cooperative victims who gave their robber everything he wanted, and got murdered for their troubles.....I seem to recall several murdered victims in a Lane Bryant store in Chicago, Illionois, herded to the back and murdered during a robbery.
So the short answer to the question of how do you know if they are going to shoot or not is....YOU DON'T! Which makes the argument 'Your life isn't worth your money' silly in it's assumption that cooperation will mean you won't die, when the outcome very well could be your money AND your life!
One thing I would remove from my mind, though....the notion of a 'basic robbery'.....that's like a 'basic murder'......there's not such thing. A robbery, especially where a weapon is involved, is a DEADLY SERIOUS proposition!
If someone wants a one size fits all response, again, there isn't one! What do you do? Well, cooperation can get you killed......fighting back can get you killed. So which one is appropriate in any given situation? It's a good topic for debate, but ultimately you pays your money and you takes your chances.....spin the wheel.
I can tell you what I have every intention of doing......handing him my wallet with one hand and drawing and emptying my gun at point blank range in to him with the other! Does it guarantee my survival? Nope, but it's a plan of action....and A plan beats no plan any day.