As Yglesias says, middle class people generally don't ride buses because they own cars and bus service often sucks. But if you make bus service better - better route integration, higher frequency, real time service information - people will choose to ride it more frequently.
Ultimately, mass transit systems of any kind, including bus systems, make a lot more sense in areas which weren't built with the idea that automobiles would be the sole means of getting around. Lower density suburbs and exurbs, particularly ones with single access road neighborhoods, will never be transit friendly. There may be bus systems in some of these places, but they will inevitably be used only by people who have no other options, because getting around by bus in these areas does indeed suck.
