Most points also apply equally to the Australian housing crisis in Sydney and Melbourne. No mortgage interest tax deduction here for home owners, although there is for investors, among various other incentives. Governments consistently fail to do anything about affordability because they're too worried about "mum and dad" investors (not to mention their own portfolios[1]).
Probably; they're both massive, no doubt about that. Interest rates are low right now, but in general you're probably paying around double the value of a property over a 30 year mortgage, that's a sizeable tax deduction.
[1] https://www.businessinsider.com.au/australias-federal-politi... "Australia's 226 federal politicians own a staggering 524 properties ..."