1) Lots of people want to live in the same relatively small area. 2) Houses take a lot of labor to make. 3) The material houses are made from take a lot of labor to extract.

If labor were cheap 2 and 3 would be cheap as well and if people did not need to live near job centers I think 1 would not be as big of a deal either.

This discussion of the problems we will have once robots take our jobs by making labor free ignores the benefits of free labor. I am skeptical of the ability of robots to take our jobs by providing free labor, but we only have to worry about the downsides of free robot labor, if we actually have free robot labor.