This is a huge component of the answer. No one wants to hear it because of what implies for their agency, but demographics is destiny.

I think this about property too.

The price of property in Australia has increased so much but the demographics aren’t there to support continued growth. Yes immigration is a thing but most immigrants don't move to Australia with $4 million(AUD) in the bank to continue fueling the boom.

What happens when demand falls ?

There’s plenty of growth, it just isn’t going to the people who work for a living, even if they’re highly educated, highly skilled, and working long hours.

Yeah, to be clear, I don’t mean that as a “them damned boomers!” post. They’re not to blame for circumstances conspiring to put life on (relatively) easy mode for them. If they’re guilty of anything (at least, many of them) it’s failing to appreciate how much harder it’s gotten to achieve what they’d consider a basic, unremarkable, ordinary, comfortable middle-class life.

Locally though there are areas that have grown quite a bit compared to others, the average misses nuance. LA has grown by a million people since 1970, while chicago has lost almost as much in that time. Are things more affordable than Chicago in Southern California? Certainly not, even if economically speaking the region is "more productive" by whatever measure.

Really what makes things cheap is a simple formulaic application of supply and demand to things like housing, which takes up the bulk of the American take home pay bar almost nothing else in comparison. Boomers had things cheap not because of riding off a population boom, but a home building boom, that zoning changes in the decades since have made impossible to replicate.

Population is still growing just fine, due to immigration. Not sure what you are saying here.