...that's not really an illustration of that. When you actually consider population and land size, the numbers don't seem so strange.
Just looking at wikipedia population and area (and a very simple scaling)
% area housing = area_house * population
aus 0.08%
nz 0.42%
us 1.82%
can 0.08%
uk 2.14%
When you consider population density, UK >> US >> NZ > Canada > Australia.
You would _expect_ countries with much more wide open space to have bigger homes, and the other nations homes aren't so big _when you consider their countries' size and population_.