I've seen some of the Australia apartments online, they are huge. A typical 2-bedroom apartment in Sydney appears to be over 100m2, and most rooms come with private toilets. Houses will be even bigger. In comparison in HK, a typical 2-bedroom apt will be less than half the size, some maybe only a third as large. Tier 1 cities in China are not much better.
If times are really hard in Sydney, 2 families can rent and fit into a 2-bedroom and live comfortably. They can share the rent, wifi, utilities and municipal bills. If they are related, brothers or sisters, they might even share meals.
In HK, if times are really hard, living on the streets will be the only option as it will be quite impossible for 2 families to share a single 40m2 apartment.