alt Hacker NewsI have no strong opinion on the original thesis but your fact doesn't make the point you think it does; you're right that no one lives in most of Australia, nearly everyone is concentrated together on the coast. Australia is a bit more urban than the USA overall from a population perspective, despite being vastly less dense overall due to the areas that no one lives in. So there would be fewer people to carry the cultural individualism.
https://www.reddit.com/r/geography/comments/1nbrov9/australi...
About 9 out of 10 Americans live in cities (incl burbs) and the same holds for Australians. Sure, there's fewer notable population centers in Australia (Sydney, Melbourne, Perth, Adelaide, Brisbane and you got nearly everyone), but there's also just 10x fewer people than in the US so that kind of matches too. I think the picture you link to distorts this, it does not account for the fact that there's simply way fewer Australians.
I'm not convinced that if there were 300m Australians, that they'd still all live in those 5 cities (with every city being 10x bigger). I think there'd be more of them.