Amazon offers people shopping for music the chance to preview short - about 30 second long or so - samples of tracks, so that those unfamiliar with an artist or their work can sample and (hopefully) buy.
Now I buy quite a lot of music, most on CD these days because I like the fiction that I own the recording rather than rent it from some digi-warehouse. Call me old-fashioned. But I am getting a tad racked-off by useless samples that do nothing to demonstrate the general character of the track in question.
In the early days of digital music vending this most often was represented by samples that encompassed only the seemingly never-ending self-indulgent introductions of some of the more flamboyant "progressive rock" tracks. Think "Bat Out Of Hell" or "Heart of the Sunrise".
I find a lot of my "new" discoveries by doing Wikipedia lateral link walks. After one that started with a favorite album of mine, Judith by Judy Collins and one of my favorite tracks from that recording City of New Orleans", I ended up trying to sample the composer's version of that song.
I offer this link to Steve Goodman's live performance of City of New Orleans so you may all share in the jaw-droppingly stupid sample lying under it. Scroll down the page and click on the round button to the left of the track name after the Amazon page loads to experience 30 seconds or so of teh stoopids.
I can only come up with one explanation: that Amazon had to license the download priced by the chord changes experienced by the listener.