That might be a climate difference — it gets below 0 Fahrenheit here every winter, as I understand it, NZ is quite a bit warmer, so maybe the strategy of “heat the core of the house and let it radiate out” works.

There are historical and cultural reasons for our poorly insulated and heated homes, but "heating the core" is not one of them.

In the last few years the central govt has brought in legislation requiring landlords to heat and insulate homes to a certain standard.