Oz stretches around thousands of miles north to south, east to west. We have significant variance in climates. A lot of area in tropical zones, stretching down to temperate and cold (particularly in the east). In the high country, extensive snowing.

Tassie gets pretty seriously cold, I think.

So, in most highly populated areas, not as cold as massachusetts, I guess, but still, pretty cold. Also, Australia is over-urbanized. Far too many population live in urban areas where they cannot access other resources to heat their homes easily.