Seriously dude, your argument makes no sense. Regardless of whether it is possible to get a gun here, it is clearly much easier in the US. You must admit that right? They're available in supermarkets without stringent background checks.
Sure it's possible to get hold of a gun here if you really want to. But the amount of work involved will inevitably put plenty of people off, and it also means that people can't rush out and get one in a rage because they've had a bad day at the office or whatever. By contrast, if you have them in supermarkets like in the US, you're advertising the idea of buying a gun to people who may never have even considered it otherwise.
The other thing about the US is it's easier to get hold of rapid fire machine gun style guns, which means that if someone does flip out, they can kill more people before they are stopped