I think you will find some of the most high density housing in the world is very expensive. What are you even on about. Land is expensive. You think detached housing is the cheapest way to build houses? You’re out if your mind. Supply and demand. Locals could live in the houses if other people weren’t coming in and buying them. How many immigrants are living in these countries? Why dont you compare that to vacant housing? The vacant housing is only a big issue in undesirable locations and you need some anyway. Like I said LVT is the way forward. Solves this problem.