I think it has more to do with the market segment to which your home belongs than it does your geography. For example, where I live only higher-end homes have built in wiring suitable for computer networking. However, homes in the mid-range can be fitted with this type of wiring as an upgrade. It's not uncommon to see it listed as an upgrade when it's present, and this is in a non-urban area of the Florida east coast.

I bootstrapped my way in to the startup scene by starting out doing in-home computer repair, so I've been in a lot of houses to see the variety and extent of the wiring available. My experience is that a homeowner only needs to experience a home wired for ethernet one time time before it becomes a "must have" on all future home purchases. Even for non-tech-savy home owners.