Was it because large areas of Australia were unsuited for the kind of agriculture practiced in New Guinea? Or did the peoples of Australia, enjoying an environment of sufficient resources, simply see no need to change their way of life?
It seems as if neither are really true. According to the Australian government’s agriculture website, as of 2025 55% of Australian land is used for agricultural purposes. While they might have had sufficient resources that could deter their need to start aggressively pursuing agriculture, their tendency to assimilate with other cultures over the course of a few millennia indicates that they slowly developed their agricultural habits over time, rather than overhauling society overnight to adapt to how the people of New Guinea lived