alt Hacker NewsCool post. I would like to learn more details!
Real question: As I understand, good insulation in your home helps two ways: Keep the heat inside in the winter, and keep the cold inside in the summer. Do I have that right? If yes, I understand there are lots of places in Australia with very light winters (or none at all), so they are mostly focused on cooling with A/C. Are you saying that installing significantly better insulation is not economically efficient for many Australia homes?
The area I'm in, Victoria, goes from about -4 overnight at the coldest, to 45 at absolute peak (Celcius). Energy wise we are a "more heating" area, but comfort wise I personally prioritise cooling.
It's a big place, the north is essentially a cooling year round climate.
Most of the older places have very little insulation, lots of airflow, single pane leaky windows.
Usually the areas you need to fix are air leakage, better windows (double glazing), then in ceiling insulation. In order of impact.
Our construction industry is pretty much broken, and considers double glazing advanced luxury alien technology... So it can cost so much to replace the old windows that you can run heat pumps as much as you like with the interest on the sum.
And without that the improvement from more diy insulation upgrades don't really achieve much in a monetary sense.
On the other side, we have a much better solar and battery uptake, and the cost to install is fair. So a typical house might be a leaky wooden crate, but with enough solar and battery to be comfortable anyway.