I’m posting here because I was surprised that these older audiobooks are available to stream. Of course, only people with the library can access them. But they must have already been part of the physical CD catalogue. I’m assuming they’re on CDs because they’re old and sound quality is definitely not modern.
So perhaps staff uploaded them to their cloud service.
You probably know about the following public domain book sources (im guessing they can be read using the Libby app or also Overdrive or other reading apps) - maybe that’s where the public library that you’re a member of got these books for their system?:
https://archive.org/details/books
ETA: I reread your post and saw you mention audiobooks. I believe the Internet Archive (and maybe the other sites I mentioned) has public domain audiobooks also.
We’re on an audiobooks sub community btw. I didn’t consider specifying but I didn’t want to bloat my post unnecessarily.
Also I see this post is supposed to have 4 (now 5) comments but I only see yours and mine, 2 are missing - I assume you or others deleted them? Or is this something to do with instances?
I see your OP, and our 3 replies. Very mysterious!