I think it's actually mostly about school shootings and 'gang violence' that drive these regulations at least here in washington, which is a little paranoid. I don't think we've had too many school shootings. I know in seattle we had a shooting OUTSIDE a high school that killed a student, but I'm not sure we've had any columbine type situations.
We're unprepared to deal with world wide 24 hour media. With 350 million people even extremely rare and weird failure modes will happen often enough for the media to fearmonger a big chunk of the population into falsely believing they're significant threat. In reality firearm homicide among teenagers is a fraction of death from auto accidents, half that of suicide, and closer to deaths from drowning. But the latter three don't make for spectacular and fear inducing news coverage.