The main factor is foreign investment in property where anybody in the world can buy land or houses in Australia, which drives up the price.
My suggestion is to limit foreign investment only to new unit complex's and new homes.
Long gone are the days when people required to gathered near prime land due to lack of transport. We now have access to amazing transport & communication options which permit the community to spread out- preferably not prime farming land.
My proven idea combines everyday shopping, household and emerging technology allowing food scraps to never end up in land fill again. This is a complete recycling system from the supermarket to the kitchen to the worm farm/composter to the garden.
Much of the water used in fire fighting is wasted, as after only brief contact with the fire it falls to the floor, whereas water that has been modified by the addition of thickener and gelling agent will stick to the burning substrate.
My idea is to use empty non leased warehouses and develop affordable open plan apartments. This was very popular when I was working in the USA. I visited many clients that had set up with massive amount of usable sub dividable space. It was secure.
Not all homeless people want to live indoors. Create a waterproof sleeping bag with a built in sleeping mat which rolls up to a lightweight easy to carry swag to give "Dignity and Warmth" to those that choose to sleep outside for just $10.
Every State has towns that for many reasons have housing that is cheap and in some cases the whole town is for sale, with some influx of people and skills these towns could be brought back to economical soundness and form strong communities again.