I agree overall, but in this case, at least according to this website, Australia is number 10 when it comes to the best countries in the world for mental healthcare- william-russell.com/…/countries-best-mental-healt…
Even if that isn’t true, the Australian healthcare system overall is pretty good.
Unfortunately, even in a good, robust system, some people slip through the cracks and end up committing atrocities. See also Anders Breivik.
Thankfully, Australia also has sensible firearms laws after the Port Arthur Massacre, so this could have been far, far worse.