I uncovered a few cassette audio books when I was purging in my basement. Some of them I had listened to and others I hadn't. I have had them for years and finding them just sparked my interest to listen to them before I purge. With all the new ways technology has developed to read e.g. ebooks, I wonder if anyone still listens to the cassette audio books now.
I have a couple of audio book Playaways. A Playaway is basically a cheap Mp3 player with an entire book recorded on it and all you have to do is plug in headphones. I bought a couple of them at they library when they stopped using them. The last time I used a book on tape was the Tales of the Otori series around 2009-2010.
Honestly, I don't know anyone who still uses cassette audio tapes. Not openly anyway, though I am sure that most people still own cassette tapes, just as I do. I still have all of the cassette tapes from my childhood. I have gone to pick my younger siblings up from school one or twice though, and have seen the school using cassette tapes, which you would think they would have CD players by now lol.