Mass killings (with any weapon) are rarer in Australia because it's a mostly homogenous, high trust culture with a solid first world police force, has solid borders to keep out unwanted stuff and people, and is prosperous enough that very few people are desperate and unnoticed enough to slip into the kind of psychosis that leads to mass killings. (at least mass killings of the kind we imagine when we hear the term). It has *expletive deleted*ck all to do with the availability of various weapons.
Yeah, mass casualty events happen at a lower rate for sure. 30 percent of Australians were born overseas, so I’m not sure what you mean by “homogenous” - it’s the democratic institution and government support that seems to keep people relatively well off that I see, not any mysterious features of the culture which is hugely impacted by immigration, much much more so than in the USA.
Having public healthcare means treatment is more likely to be available to the mentally ill, and having industrial relations that actually prevent unfair or capricious firings reduces the level of workplace and financial stress that frequently causes mass shootings in the USA.
On an incident by incident basis, though, it is obviously the case that fewer people die when knives are the most deadly instrument available to the average mentally ill attacker. Sumpnz’s point is transparently ridiculous - it’s akin to arguing that an attempted suitcase nuke attack is less deadly than other forms if the batteries go out and the bomb doesn’t detonate. The randomness of specific incidents changes body counts; it’s still absurd to say the risk to human life changes not at all with the selected weapons.