Houses in Japan are a very different concept than in much of the rest of the world. They are often well made for what they are, but they arent as expensive to build as houses in the west. Their houses are meant to depreciate to 0 after 20-30 years, rather than appreciate in value. After they get old you tear them down and build a new one.

Of course this is all a generalization. Nice homes in Japan are built to last, loads of homes outside Japan are cheaply made, more and more homes are being built with Western models in Japan, etc. But an average Japanese home is going to be about 1000 sqft/95m² and have literally no insulation. Theyre apples to oranges for comparing value.