It‘s not necessarily that it‘s cheap, but also constant updating of building regulations when more powerful earthquakes hit. In 1990 if you were buying a house older than ten years it might be the difference between life and death.
The latest (‘80s) regulation buildings have held up even through the 2011 quake, so this is the first generation of 50 year old buildings that also meet the safety standards of their day.
According to the Japanese Ministry of Land, Industry, Transportation and Tourism, 29% of kyu-taishin buildings suffered major damage in the 1995 Great Hanshin earthquake, with 14% totally collapsing.
> For post-1981 shin-taishin buildings, the rates were 8% and 3% respectively. Reducing your chances of damage by two thirds, or of collapse by nearly four fifths, is pretty substantial. https://resources.realestate.co.jp/living/are-you-prepared-f...
Yeah, any you can't improve much on these rates anyway from now on. Diminutive returns - no reason for the value of such properties built after 81 to go to zero if they are well built.
The latest (‘80s) regulation buildings have held up even through the 2011 quake, so this is the first generation of 50 year old buildings that also meet the safety standards of their day.