Thanks, David and BigA, for making such excellent points. I agree with pretty much all of it...and yep, in the book
So we've got this spectrum, and the system we've deployed as "digital" is a market failure. How about perhaps using it for something useful? Or lose/abandon it? As David said, "radio" means much more now. Why can't "digital"?
In quite a significant number of perceptual studies, I've found that digital is perceived to be mp3s, to some extent, CDs and of course anything that comes over a stream. So,to simplify, streams are digital. AM and FM are not.
I believe the perception is so locked-in that it won't or can't change. Ancient media can't possibly be digital in the listener's minds. So the idea of buying a "digital radio" is pretty much an idea of committing an anachronism.
Of course, to most people "digital audio" means 128 kbs mp3's. It does not represent higher quality... it is synonymous with accessibility and portability.