And if the gunman is standing in a crowd you'll still shoot him? Last I saw 9mm rounds weren't very discriminating with which type of tissue they penetrate.
Those situations are very rare. However, if the situation ever arose, the armed civilian would have to be sure of his/her target and what's beyond it. On the other hand, an opportunity might present it self where the armed civilian can get a clean shot. Otherwise, the gunman can and will kill as many people at his unfettered discretion.
If there is no need for people carrying concealed weapons, what would be the harm in offering it? Personally, I've never felt threatened in Canada either, but then again, I'm a pretty big guy. Who to say that will always be the case for me? Who's to say that's the case for others? Nonetheless, the option is unavailable. I have CCW permits from Utah and New Hampshire, but it doesn't necessarily mean I will ever carry in those states or others that offer reciprocity - all I'd need to do is to meet the residency requirement. I appreciate the confidence and hospitality though. It's remarkable that those states issued me a CCW permit, but my own province won't.