Uh,,,I think you're terribly mistaken on pretty much everything you said.
First off, we have military and police.
Two, whether you have a gun or not, when a group of terrorists start randomly shooting at a crowd of people who are just relaxing and enjoying life, some are sure to get shot and killed and wounded.
It's a surprise attack and I highly doubt that typical civilian who are not trained for situations like that would suddenly get up and start fighting back.
Americans are humans and French or people in any other countries are not any different in responding to situations like that.
Plus, shooting is also not that easy for untrained people unless a target is very up close AND either still or very slow-moving.
No doubt that highly trained people can of course still get wounded or killed.
Also, how many people fought back with guns in recent or any US mass shooting accidents?? I'm pretty sure the answer is none!
And why the hell would a civilian carry a gun on a everyday life in a stable country?
Terror attack is a different category, but as I said earlier, US is about the only country where unnecessary deaths occur way too often because it is easy to get a gun, or people own guns.
This kind of craziness never happens in other developed countries!!!
Do you know why? Go back to my older comments, please.
It's not Disney movie, it is called reality!