The quantity of roads in length and width available increases and I wouldn't be surprised if the cost of supporting that infrastructure rises with the square of

The quantity of roads in length and width available increases and I wouldn't be surprised if the cost of supporting that infrastructure rises with the square of the land accessible by those roads (i.e. one long road is much cheaper to maintain that a grid of roads with equivalent length in miles). If the homeowners are only allowed to drive on the roads that were there when they bought their home the situation would be fair. Education on the other hand I expect to remain fairly constant on a per unit (child) basis once a school hits 150 children per grade.