Because idiots spend money on ads that pay for the station to exist. Radio is the same way. Nobody cares about HD, but they still advertise it because a small number (1-3 people) will actually buy one.
I might have to disagree on the "HD Radio" one. First, ibiquity is a bunch of cheats. HD doesn't actually stand for anything officially. They want you to think it does though. Second, it's crap. Fortunately the public is buying into this crap like they do for most of the other garbage. So everyone once in a while the idiots get something right.