You know what assuming gets you, right? And I hate to tell you, that gunfights due to armed guards are not as common as you seem to think. The shootout that you are talking about above, the ones where the robbers had freaking AUTOMATIC rifles(AK47s to be exact) with hundreds upon hundreds of rounds, body armour, and other weapons, started when they opened fire on POLICE OFFICERS. Who were just doing their jobs. What the heck are they supposed to do? Let the robbers go because they might open fire? No. They start doing that, and the criminals would continue to use the same M.O. with bank robberies. This isn't like television shows where the cops put down their weapons because a criminal tells them to. That isn't the real world, and that actually irks me when watching the show, as I removes any sense of realness to it.
And the BEST part of the above example? The only ones killed were the piece of **** robbers. They reaped what they sowed.
I wouldn't have wanted to be in that American bank while it was robbed.
The reason why the robbers came loaded for bear is they were expected to shoot their way out. If they came to Canada, they could have robbed a bank with a small pointy object like screw driver. How much money are they going to get? A couple of thousands in marked bills and a packet of exploding red dye. That's hardly worth killing or dying.
Also you never mentioned the police that were injured, the innocent bystanders who were traumatized or the effect shooting and killing someone would have on anyone including a police officer.
How was your day honey? Oh you know, the same old, same old... oh yes, I nearly forgot. I did I empty my assault weapon into a robber's face today. I splattered their brains all over the street. But other than that, not so bad. How was your day?
I doubt armed guards reduce the incidence of armed robberies. It might cause the robbers to go after softer targets and it certainly raises the stakes.
I hope Canadian banks never use armed guards except in exceptional circumstances.