My brother and sister in law bring that up. They are right wing ultra religious nuts though. What makes it weirder is that she's half Mexican.
Anyway, places like Honduras for example are ridiculously poor and more importantly lawless. I'd expect it to be going tits up there when some people have absolutely nothing to lose.
The issue I'd suggest is more to do with the type of murders. A whole drug gang getting wiped out in rural Mexico doesn't quite have the same impact as dozens of young, innocent kids that are in their school.
The one thing I do kind of understand is the paranoia that forces you into getting a gun. The other problem though is that it doesn't quite end there. You don't end up buying a hand gun, you get the whole modern warfare arsenal then become defensive about your rights.
Sandy Hook as Stupie said should have changed the culture the same way that Dunblane had. It's not going to stop, ever.