Come On De Selby, your neither retarded, nor ESL. Sentence structure means something. But let me lay it out for you:
It is an objective fact that populations with lower cultural diversity and higher interpersonal trust have less interpersonal violence. I don't "think people decide to behave more peaceably by magic", there's plenty of repeatable studies among populations large and small that show this trait. Australia, by and large, has a LOT of buy in and assimilation to the "Australian" culture, that is the societal values and mores that bind the population into a cohesive culture. No this isn't done b a 30min citizenship test, but it is helped by having hard to bypass borders, and non rubber stamp immigration laws. Helped, not 100% caused, before you jump on that. By and Large, the people that choose to immigrate to Australia, and jump through the hoops to do so, do it because they want to be Australian, and largely assimilate to those values and mores. Not 100%, Religion is still a thing, and you guys have the whole Aboriginal Gordian not going on, but in comparison to the US, and much of the recent immigration to Europe, Australia has lower variations in it's base culture, and is a higher interpersonal trust society. <- Those traits are linked to lower interpersonal violence regardless of weapons availability throughout known history.
You also conveniently ignored the second part of my post that you quoted:
We weren't discussing the ease of access to healthcare and employment benefits, we were discussing how people felt about them. Both the US and Australia regularly survey their populations on Stress and mental health, and the results of those studies are public and easily googleable. True, they studies aren't identical in both countries, but they are very similar and show trends in the countries nicely. Your hypothesis that Australians are less stressed is wrong. Australians are similarly stressed. For all that access to this that or the other may be measurably easier in Australia, it does not seem to translate to less stress about those functions. That's the problem with people's feelings. You can tell them over and over again how great the economy is their safety net is and they might not agree and feel good about it. Australians are not less stressed on a macro level than Americans, even if that hurts your personal feels about how great healthcare and employment is there.