And building code too. There are plenty of cost-efficient designs built in Europe that can't be built here because we effectively require e.g. doubly-loaded cor

And building code too. There are plenty of cost-efficient designs built in Europe that can't be built here because we effectively require e.g. doubly-loaded corridors through stairwell requirements. The Europeans can put up more housing units on a smaller plot of land than we can, and for a cheaper price, because of these requirements.