Adam Lanza’s mother was a gun fanatic and taught her son to use them. He took his mother’s guns into the school because they were available, and he was comfortable with shooting them. If he had grown up in a household, like mine, where guns were not a part of his life and were not accessible, maybe he would’ve used a knife or a hunting rifle. He certainly couldn’t have used a car. And, as I mentioned, we’re already starting to add bollards to sidewalks to prevent vehicle attacks. When you start to take away mass killers’ options, you can control public spaces better, create safe zones and limit the casualties when someone does attack.
As for whether terrorism is happening more often now, it doesn’t seem so, though I’m only seeing data back to 1970. Terrorism killed more Westerners in the ’70s and ’80s, this says.
Treating the root cause would be a bit more complicated than adding security at hotels because mass killers have so many different motives. Oklahoma City was retribution against the Feds for Waco and Ruby Ridge. Charleston was racism. San Bernardino and Orlando were widespread anti-American sentiment and U.S. intervention in the Middle East creating sympathy for a media-savvy jihadi ‘state’ that eventually put out a call for lone wolf attacks in the West. Newtown doesn’t even have a known motive.