I think the OP might have been confused between the use of the words: uninhabited and uninhabitable. In fact, much of Australia could be inhabited even the more arid areas are technically habitable. If you look around the world, you’ll find people living comfortably in a wide range of environments from arid to jungle.
Actually, Oz’s population is growing rapidly compared to many countries. The real issue isn’t the amount of immigration, it’s future growth rates and whether available resources are keeping up with the growth rates: houses, jobs, services, roads, infrastructure, etc..
In fact, these issues are common in rapidly growing population centers: property prices are rising rapidly creating a generation of homelessness and unaffordability. But the population growth is a marker of these countries’ success in development and attracting talent and investments.
The policies that control new builds (and therefore prices) are based on old assumptions, old practices and out of date ideas. But of course, immigrants and young people don’t vote (well, in Oz, they do!) in most countries, they don’t because they can’t… so of course, not much changes.