I've actually lived in Australia and America, so I know a little bit about their gun laws. There's essentially nothing stopping me from buying a handgun in Australia (as long as I own a gun safe and am a member of the gun club) and shooting a handful of people at my college besides like, a ridiculous wait time, and the simple fact that I don't want to. Also, anyone who's ignoring the influx of illegal handguns appearing in Melbourne despite the gun laws is living in la-la land.
Australia has excellent mental health institutions though, and the high-schools work
way differently. There are so many options available to people who are struggling with anything really. All the kids are generally on a level-field as well. This is at the sacrifice of a lot of privacy and personal freedoms though lol, at-least at my (australian) high-school, uniform standards were ridiculously strict, but from what I observed, there were really only 1 or 2 kids in the entire grade who struggled socially. In comparison the average American public school is comparable to a prison, and yet somehow offer no security at the same time.
Like, I'm not saying you have to cavity search everybody as they walk through the door, but Cruz wasn't even a student at the school he shot up, and he brought his gun in in a loving duffle bag. All it would take is some dude standing outside the front door to ask "What's in the bag", and that's all it takes. Stop the gun free zone bullstuff. It doesn't work.
Australia does have some sensible gun control, obviously they don't allow you to own Le Scary Assault Media Boomstick, or a pitbull, but for the guns you can buy you must have a gun-safe and a place to shoot it. There's a ton of government-owner communication. I don't even think this type of regulation would face much resistance, but it's just simply not the type of regulation anybody is pushing for. Banning certain chunks of metal is insane. The regulation should be owner-based.