Now, I understand WHY a city is more expensive. Because stuff costs more, because there is more tax, more demand for less space, etc etc etc. But WHY are these underlying services more expensive?
Taxes: Sure, there are more people to service and a few more services (pedestrian crossing signals) but there are a lot more people who pay for them. And many don't even live in the city but spend money there!
Space: So the land has more demand. But why can't we go vertical as needed? Most cities have less than 10 buildings over 20 floors.
Restaurants/Movies/Clubs/etc There are a lot more customers to provide for revenues. More economies of scale, should be cheaper.
Infrastructure How is it that cabling/piping/ducting a building is more expensive than across 25 acres of a suburban neighborhood? Cities may have public transit, but less roads to maintain, less area to cleanup, less trash pickup points, etc.
What am I missing?
Cities have to pay pension and healthcare for retired city employees. For newer suburbs, there is no such requirement.