Not to mention the point, widely missed, I'm reasonably sure entirely intentionally, is that the point of gun control is to reduce the number of guns present, make it easier to confirm someone owns the guns, and make it more difficult for guns to be obtained by someone who shouldn't have them over all.
It doesn't matter if they don't follow it, if everyone else does they'll still have a bitch of a time getting weapons and it'll be much easier to track down the people selling the weapons to those who shouldn't have them.
It's not perfect, but it's better than having a minigun section in walmart.