Tokyo builds a lot because they tear down homes after 30-40 years to rebuild them. You can't judge Tokyo's property market by new housing starts, and the fact that housing depreciates (rather than appreciates) scares away all the speculators.
In Japan, the real estate system is designed to ensure affordability of homes.
In Australia, the real estate system is designed to encourage and maximise real estate investment as a no-effort wealth multiplier for (literal) rent-seekers. See for example the policy of "negative gearing" where the tax system subsidises those buying investment properties. Those that took advantage are such a powerful block that no politician of any stripe has the gumption to sunset this policy.