50 years ago in that same "deadly gun culture" you could purchase a gun from a catalog and have it shipped to your house through the mail. No one used them to shoot random school children. Today, you have to go through a background check, wait for a while, in some places you have to present an acceptable reason, all before you can obtain a firearm. People are using them to shoot random school children.
I'll pose it to you, advising that I've posed this question multiple times and never received a solid answer, just more anti-gun rhetoric:
What changed between the time you could easily obtain a gun with no questions asked but live in safety, and the time it was becoming increasingly difficult to obtain a gun and your safety was threatened? Hint, it wasn't the guns.