The tl;dr is that Australia started a fibre-to-the-premises project for the whole country (93% of premises, plus rural 7% on wireless), then a conservative government got in power and decided to deliberately destroy it. To do this, they changed it to fibre-to-the-node (DSL) instead. Instead of gigabit to the home, they're spending more money providing people with connections anywhere between 4mbps and 100 at the absolute most, with no possibility of upgrades. The cost to do this, is, of course, far more money in the long term than installing the fibre. Some people in metropolitan areas will get connected to the existing coaxial network, which is going to have huge contention problems as it's stretched far beyond what it was ever intended for.
It's the biggest trainwreck of an infrastructure project in Australia's history and will set every person and business back for decades, and the blame lies squarely with the Liberal Party.
The current head of the project has gone on record saying that Australians don't want fast internet and wouldn't use it if it was free.