General population don't practice ramming car into crowd. Those are not hobbies. So, when mentally ill people want to cause harm they don't use those methods. It does not normally comes to mind.

But, shooting is common. It's a hobby. A killing machine is normalized and it becomes a culture. So, those mentally ill men feels completely normal to shoot people when they go crazy.

Consider this: ramming car into objects becomes a hobby and people starts to do that and take pride in it. They practice it every week. Then, those mentally ills will start using those methods. And then government will ban riding a car. But, this is not happening, just a hypothesis. You can replace car with other objects you can think of here.

That's why countries where gun are banned for general population, does not have mass murder by "common people" like USA. There are mentally ill people everywhere, not just in USA. This is the point gun lovers don't understand.