It is not that puzzling if you live in Australia and pay attention to the economy.
We have a residential real estate bubble that is worse than that of the US in 2006. Median house price to median income ratios in Sydney are worse than almost anywhere but Hong Kong. We have the highest per capita private mortgage debt of any country. This represents a massive unproductive overhead on the Australian economy, as the elevated cost of shelter flows into all other costs. Tax arrangements in Australia make leveraged real estate speculation more favourable than any other kind of investment, especially productive investment with any sort of risk attached. More than 50% of the existing mortgage debt is owed overseas via the big 4 Australian banks, so we are constantly exporting what wealth we have overseas as interest, so we can sell shitty houses built in the 1960s to each other for AUD1.2 million.
Many sectors of the Australian economy are filled by a limited number of participants (e.g. banking, supermarkets, hardware, telecommunications, petrol) who are most interested in rent seeking, and not interested in competing with each other.
The Australian economy has been a net importer of capital every year since the early 1970s, an almost ever year since post WW2. If you run a current account deficit so egregiously, the result is you sell off all your productive assets to stay solvent. This also means the pool of Australian capital available to invest in Australia itself is very limited.
Australia has some of the highest immigration intake in the developed world, but no long term infrastructure planning to account for such population growth. Since most immigration increases the population of the large cities, the lack of investment in transport infrastructure is most apparent. We grow the economy by increasing the captias. Per capital net disposable income has been static or falling for the last 5 years.
Politically, Australia has been without vision for real economic development outside rewarding entrenched rent seekers for the last 20 years. We have not seen any significant increases in productivity over that period.