Those one adult households are likely to be full time workers. In two income households you either have one full time worker or two part time workers or one full time and one part time worker or two full time workers. Would be rare to find a household with just one part time worker.
So using the median individual before tax wage (i.e. a single wage) to determine affordability levels skews the results downwards. Obviously even two income households are struggling at the moment, especially with childcare costs and other costs, but if want to measure housing affordability and cost of living need to do it at a household level, and combined in a household suspect they are earning more than the median wage combined (especially when including other benefits).
Here you go - the median household income in Australia, before tax, is roughly $1700 per week, or roughly $94,000per year. See - https://www.abs.gov.au/household-income
The ABS tries to do a standardised test, but at the end of the day when they standardise they seek to equalise household numbers, but that is irrelevant from just working out median household income. Also the lower standardised figures for the ABS are after tax (disposable income) and these are still higher than the individual median gross wage, i.e before tax, in the opening post. Even the SMH uses the actual figues: disallowed/money/planning-and-budgeting/how-wealthy-are-you-compared-with-other-australians-20180410-p4z8s4.html
