...basically fall into two categories: The Northern systems that were in-place prior to the post-WWII "auto explosion," and the newer systems of the South and West that serve the urban underclass almost exclusively.
The older systems up North serve people across the entire economic spectrum. They were built and expanded at a time when few could afford cars and fares for buses and subways were cheap, in a dense environment where many who could afford a car had no desire to own one! Most riders still don't want to drive a car into Manhattan or downtown Philly every day.
Everything changed in the fifteen years following World War II. We became a "car society," and nothing short of $10 gasoline or restricting auto access to city centers is going to get people out of those cars and onto the bus. Look at L.A.'s public transit system, see who rides it, then look at the Hollywood Freeway or I-5.
There is absolutely no incentive to ride WAVE. I've lived here for sixteen years (this time) and have never even THOUGHT about riding a WAVE bus. In my vehicle I can set the temperature where I want it and listen to what I want to hear.
Public transit systems..