Now you're just being a jackass and you know it.
But.....I'll bite: What's your answer to that scenario?
Here's the deal. Two guys walk into a nearly deserted Denny's restaurant at 5:50am carrying firearms. Joe citizen now has a little bit less stress and a little bit more time to evaluate the situation. Are there bystanders in the line of fire? Is there cover or at least concealment available? The criminals are likely to be most concerned about getting what they can quickly and quietly and getting the heck out of there. The all powerful "element of surprise" is in favor of the customer with the gun.
The customer with the gun has no idea what will happen next. The criminals may take the money and run. The criminals may get the money and shoot all the witnesses. A cop or anybody else might walk through the door and the criminals might start shooting. A siren might be heard in the distance and they criminals might grab a bystander for a hostage. The situation could change in any number of ways in the matter of a split second.
If the situation does change, the customer with the gun cannot possibly predict how. That is why it is vitally important to take defensive action during the time frame that the customer with the gun has available while the situation remains as evaluted. Cover and/or concealment availalbe. Clear shot available. Criminals not expecting to be fired upon. Chances are much greater for a successful defensive attack when the defender has a full evaluation of the situation, and the situation is currently stable.
Once "all hell breaks loose" the situation will be changing every fraction of a second. It is just not tactically sound to wait until the attack is in full swing before beginning a defensive attack. Especially in the restaurant robbery scenario where once the initial entry is made and no immediate resistence is met, it is very likely that the criminals were expecting no resistence to be offered.
Once the criminals start shooting the primary goal becomes seeking cover rather than returning fire. Sure, return fire on the way to obtaining cover, but when being fired upon the first and primary goal becomes to gain safe cover from the enemy fire and if safe cover can be obtained without returning fire, it is better to do so. Let the criminals shoot their bullets while you are safely behind cover. That increases the chance they will run out of rounds before you do.
You contradict yourself, Rich_S. You say you would not defend a perfect stranger, then a few posts later you say you will start shooting if hostages are taken. The idea of returning fire immediately when being fired upon is best left to the RAMBO movies.
It is most tactically sound to begin a defensive attack before the aggressors expect it, and before the aggressor's attack is in full motion.