It isn’t compared to traditionally built homes is the US. Most material used is recyclable and the building it takes a fraction of the time saving a lot of money. Also the seismic stability systems that are designed in are also cheaper then retrofits on traditional structures. If homes are rebuilt every 30 years homes can constantly be upgraded with the latest technologies while minimizing dangers from unsafe building materials such as asbestos. All of these factors ensure a better quality of life for the county as a whole. Probably wouldn’t work in most places but a county with the climate and population of Japan its a really good system.