Because there's not a section in walmart to buy bombs. Because there's no national bomb association that says bombs are a 2nd amendment right and everyone is entitled to their bombs. When someone makes a bomb, they have to go through a lot of trouble to make one. It's not just that everyone who has a dispute with their mom, in the heat of the moment pick up their gun and go slaughter people. Because it takes a cold calculating sociopath to make a bomb and kill people with it. That's why.