The reality about big cities that Rex doesn't yet understand, isn't that they're built to accommodate for big people, but rather, they are built big to have more room for more little people. Sadly however, some of those little people start to think they are bigger than they really are, through jobs, wealth, or other forms of status. These "big" people then turn around and make the big city bigger, making big prices so the little people stay feeling little and the big people stay feeling big.
It's a big bunch of silliness if you ask me. It's the little things in life that make it big!