In Australia the root cause is likely policy that rewards rather than penalises multiple home ownership as investment, leading to flow on effects that raise prices and doesn't boost building.

However not all would agree with that and each stake holding group has a different take on things.

eg: The Australian home builders industry group, the HIA, throw shade on increased costs and government fees and push back on other hot takes here:

https://hia.com.au/our-industry/newsroom/economic-research-a...

I lived through my peers struggling to get a single house built or rennovated in early 80's and later and watched finnancial incentives made it easier and easier to get a second, a third, a fourth house just as happens in Monopoly

Hand in hand with that, those people with houses as assets could afford to bid higher against each other for that fifth house .. pushing out those younger and just entering the scene.

It's hard to discount the rapid rise of a landlord class as being a significant factor.