The article just says that there were changes at the beginning of the millennium, and not what they were. I suspect they were the changes John Howard brought in just as he was about to lose government, which were very poor fiscal policies, but that successive governments have failed to reverse, because it would be political suicide.
To a large extent, I agree with happy. I bought my first house with a 17.5% mortgage, and it was very run down, and needed everything fixed. Most young people bought houses nowhere near their parents, and in new, outer suburbs. Today’s young people appear to expect to buy near their parents in middle suburbs. But whereas we had a reasonable commute, the outer suburbs are a lot further out now, so the commute is brutal.
Australia is one of the most urbanised countries in the world - about 90% live in cities as against 82% in USA, and something similar in Canada. We don’t have many cities either. We have almost 27 million people, with almost 5 million living in each of Melbourne and Sydney. Brisbane and Perth have over 2 million each, and Darwin is the 17th largest with a bit over 100 thousand, so the housing problems really boil down to housing problems in Melbourne and Sydney, and, to a lesser extent Brisbane and Perth. One of the reasons Melbourne has recently overtaken Sydney in population is that the problem is worse in Sydney, as Melbourne currently has more lower priced housing stock. The federal government has recently released new policies and money to address the issues and has targeted more new housing for Sydney than Melbourne.
Both cities have struggled to decentralise, so there’s a lot of commuting.
To add to the problems, since about 2009, there have been many homes destroyed in floods and fires on the outskirts of all these cities.
We also have one of the higher rates of migrants. 30% of people came from somewhere else, compared to 15% in the US and 21% in Canada. They’ve all got to be housed somewhere. We also have a very high number of international students.
However, it should also be noted that both Sydney and Melbourne have appeared in the top ten in various lists of “the most liveable city in the world” for much of this century, so they’re both very good places to live.
Note: Australia is a similar size to the contiguous USA, which is roughly two thirds the size of Canada, which is why I compared the three countries.