I was in a US social security office yesterday (just moved here). Government place, long line, take a number, have your bag searched and be waved down with a weapons detector as standard. I got involved in a conversation with an American man sitting next to me, who was interested in differences with the UK system. In his 40s, I would guess he was gay, he had lived in LA for more than a decade. So, old enough to be informed, plenty of access to alternative news, a good chance if not heterosexual he's outside the right wing proscribed mainstream.
I commented that we wouldn't have security searches at our job centres (the closest equivalent). His response - we had a little thing called the Twin Towers. I mildly explained that after a shocking school shooting in Scotland in the 90s, our government had a quick and decisive hand gun amnesty and they are now not at large among the general population. Reminded him about the IRA's campaign in the UK, among other terrorist attacks.
My point being, the average person here is just so ill informed and afraid. 9/11 has entered cultural folklore as the unthinking justification for many cultural phenomena that pre date it by decades. How ironic that their solution to problems - real and perceived - to be armed, is what is actually killing people in their droves.