There is a used house market, but it is quite small. The general idea is that used houses are dirty, that only poor people want one, that they are nothing but trouble (from a home repair perspective), and that they are entirely undesirable. So nearly all old houses are knocked down as soon as the owner dies or sells. It's crazy and wasteful, but that's how it is. The government has been making talking about making a tiny effort to reverse this in the past few years, but so far they haven't done anything.

Glad you enjoy them :)