I like big arguments!
I'm not sure what stores you're referring to, because if you're buying from a dealer, this statement is patently false.
Maybe it's not quite like that anymore, or it's partially true:
- I saw portrayals of firearms (mostly hunting shotguns) being sold at convenience stores in several movies (which were also a plot device, as usually they were stolen and used against the owner). Assuming that there's at least SOME truth in that (e.g. that any kind of store can be licensed to sell them), that's still 100 times more liberal than anywhere else in the world.
- Being an avid reader of Italian weaponry magazines in the past, I followed legal/licensing issues with interest. Many readers reported on the comparatively liberal -practically free- gun ownership in the USA, contrasting to the Italian situation where you needed to be no less than a Noble with a political nomination, to be able to get a handgun carry. They also mentioned wide availability at least of hunting arms (smoothbore 12 gauge shotguns were quite more deregulated than handguns), and the lack of need to show an ID card, again, at least for hunting shotguns.
- Of course, all of that was in 1999/2000, so pre-9/11, and before many more clamorous shootings (though after Columbine). Things might have changed since then, but still, the USA is VERY liberal compared to anywhere else regarding legal gun ownership.
- The situation in the USA cannot be compared to the compulsory ownership of an assault rifle as in e.g. Switzerland or some Greek National Guard members: in those cases, you are formally charged with keeping a gun, just like a service soldier is, and you can't use it for sport or fun: on the opposite, you're charged with securely keeping it and also maintaining it (it gets officially inspected regularly, like a service soldier's). Also, you are generally not issued ammo to keep with it, unless called for service.