Ah yes. I was thinking about the space in the cities that we already have. Some cities have no other choice but to expand vertically. In places where there is space, we still don't see those apartment buildings.

But there are always exceptions. Like Whittier in Alaska, in the mountains... yet, the entire town is in one centralized building. https://pbs.twimg.com/media/FqLhFoQWwAIE5bg.jpg:large