The places where cities make sense are generally the places where they already are. You could hypothetically build the trappings of a new city in North Dakota or West Texas, but who is going to move to a place which is just a bunch of empty buildings surrounded by farmland? You can already buy a house in such places for less than it costs for one in a major city but there is a reason that people don't.

Whereas if you would just rezone the areas with high demand to allow new construction to actually happen there then you don't need the government to raise and spend a ton of money, all you need them to do is to stop prohibiting the thing people would otherwise be doing.

All the 'large areas of land' that people want to live in already have dense cities. This sort of ideas have been tried again and again, and it falls apart because people just don't want to move there.

Would you be enthusiastic about relocating if this was forty minutes away from Vegas in the desert?