There are plenty of factors. Most of the country has reasonably temperate weather all year round, especially on the more populous north island. Then you have the just get on with it throw it together attitude that used to dominate the rural areas, so you're starting from a really low point.
Starting from that low point it seems that its been hard to raise the bar. The cost of materials must play a part there. There's also been ongoing and continual issues with the companies that actually do the building and/or manufacture the materials being both intertwined and in monopoly positions.
I just had my house extended. Any new windows had to be double glazed, which is only a recent change. In many European countries its now triple. The new parts of my house are considerably warmer, and the original build was only 15 years old!
> The barefoot thing is just cultural, not because people can't afford shoes.
Yeah, I have a hard time persuading my kids to wear shoes. He could be describing my town and its not a poor area at all.