The real problem is not the cost of actually building a house. Modular housing can be purchased, but people who have new houses put up do not chose such basic designs. Rental housing is largely designed for the wrong people. Unless government takes the lead and actually builds modular housing for the poor the situation will stay the same. Costs involved in getting land ready for construction is the real problem. Land levelling and servicing is very expensive. Councils are the main reason for this. There is no competition is regard to charges. A builder must pay fees to councils at council set rates.
Without established affordable housing it is virtually impossible for a person to contribute to society by holding down a job. Even when learning job skills rents are very high for accommodation near educational institutions. User certainly pays in this regard. Low income earners are also competing with each other to get the cheapest third of advertised rentals. Plenty of houses are available in rural areas of course. Living off welfare payment is almost mandatory there because there is no work. By definition where there is work rents are high.