Something like 30% of Australian households own their home outright. This explains the low debt when using averages and medians.
"According to the 2016 Census of Population and Housing (Census), there were nearly 8.3 million households in Australia.Where household tenure was known:67% (5.4 million households) were home owners:32% (2.6 million households) without a mortgage35% (2.9 million households) with a mortgage"
