This ignores many things. Legal requirements have pushed up home and lot sizes. In the suburbs of NYC a drive will take you from 1910 era suburbs with 800 square foot homes where 80% of the lot is building or useful infrastructure that are now illegal to build, to just built 4000 square foot mansions on lots large enough for apartment buildings with a mandated 20-30% lot coverage maximum. You are also ignoring the fact that even with modern power appliances and automation it takes a lot of time money and people to maintain those new lager homes.