Despite the fact that MASS shooting is on the rise in USA, there is very little USA government is doing to stop these MASS shootings in future. Joe Biden too not very much in favour of gun law that let anyone buy a gun hut still there is no legislation from federal government.
So what you're really asking is why authoritarian restrictions aren't being passed against the popular will of the people *and* the supreme law of the land in a representative democracy.
I think you are right, there are not many in USA that are in favor of ban on guns. So this will go on.