>>1747287The sidewalks and roads aren't getting more expensive, they just need to effectively have more sidewalks and roadage per person. it's basically just a matter of surface area. consider if you need to fit x number of things in cells with y dimensions, and each cell has a thick border around it. the more things you are able to fit into each cell, then that necessarily means there will be less cells required, meaning less area taken up by border. now just replace "things" with "people," "cells" with "residential lots," and "borders" with "roads and curbs."
