You sure about that? Ethan Peck is four years older than Nimoy was when he started to play Spock. The current iteration of Spock only feels younger because Ethan clearly has a good skincare routine.

I think this is the correct answer, outside of large cities it is not legal to build apartments or row houses in many places in the States. It would probably be significantly easier to skirt the zoning laws to buy a plot of land and put 100 tiny houses on it, than to attempt to get some sort exception granted to the zoning in order to build an apartment or row house.