Only one or two of the suburbs listed are actually considered inner city.

As someone who does live in the inner-city of Sydney and pay $3100USD/month for a shoebox. I would be incredulous if there were a large amount of vacancies beyond normal turnover.

There are usually bidding wars for property sales (most inner-city properties are sold by auction) and dozens of applications for rentals.

I've lived in the inner-west all my life & I know 5 or so squatters. Yep. There are vacant buildings everywhere you probably just don't know it. There's a whole world outside the market & we need to encourage this sort of thing, or else a city becomes locked into mortgages with little job flexibility. The ability to live cheaply in a city is very important. High costs to maintain a basic lifestyle mean less risk taken, less businesses started, less innovation, less arts. In total contrast to Sydney is Berlin: high unemployment, very low cost of living, tons of start-ups, tons of arts.