Off hand, I'd guess that the contractor who builds the house puts in the cheapest thing he can find, it works until it breaks and the HVAC guys get called "cuz the heat's broke". If a new thermostat is required, the cycle begins again.

If this is indeed the case, then its no surprise that thermostats are the most boring, user unfriendly things imaginable because they are more or less universally selected by price alone.