I'm not comparing the US to Australia. I'm comparing Australia to itself, whereby it has seen a decrease in mass killings since passing the gun law. The graph specifically states that mass shootings are caused by crazy people. If that's the case, then the decrease in mass shootings since in Australia since 1996 can only mean that gun laws reduce the amount of crazy people in a country.
(preemptive sidenote, before anyone points me towards https://en.wikipedia.org/wiki/Australian_mass_murders as evidence that mass murders happen with the same frequency after the law was passed in 1996, note that the list there accounts for other causes such as arson after 1996, but only shootings before 1996, ignoring incidents like the Whiskey Au Go Go fire in Brisbane or "the Downunder Hostel fire in Sydney- It's a crappy source).
1) The systemic racism problem we face in America that ooh, say, ~50% of the population does not even acknowledge exists.
2) A society that stigmatizes mental illness.
3) A healthcare system that actively discourages preventative care, that leaves its users destitute and in debt.
4) A corporatocracy that gives workers as little as humanly possible in jobs that take upwards of 40-70+ hrs a week of their lives.
and maybe 5 could be something to do with gun control.
Right now, people's answer to shootings like this is to blame it on crazy people. Often to move the conversation away from gun control. Unfortunately 'crazy people' simply doesn't cut it as an explanation when it is happening with frighteningly frequent occurrence. If we continue to refuse to discuss guns as a potential issue then lets at least move onto some of the other potential causes rather than just sweeping the whole thing under the rug as down to a few bad eggs. At this stage it's painfully clear that it's not just 'a few bad eggs' and our ignorance of this is quite literally proving fatal.
Disclaimer on guns: Personally, I do believe that gun control would help the situation, but I also recognize that gun control is not a perfect solution, nor is it really pragmatic and feasible solution in the US.