This reminds me of the widespread move to change from “private message” to “direct message” on platforms like facebook and twitter. A subtle hint in the UI as to how things really work.

Twitter has always, to my knowledge, called them DMs. I’ve always hated FB messaging, despite using it out of necessity occasionally, so I can’t speak to if/when the naming scheme changed there. That said, a bunch of smaller messaging sites made that shift, so your core point is valid, I just think you overshot with your examples potentially.

An interesting exception - it is still Audible's policy to say you keep everything you've bought if you decide to cancel a subscription. This still ties those books to their app but it seems like the best we can hope for given the alternative choice.

There have been at various times scripts found on GitHub, BitBucket and the rest that will convert the files to MP3, effectively breaking out of the DRM, but this has been hit or miss in my experience.

My pipe dream for all of these services is still a buyout clause which would provide you with the unprotected files for a fee, but with the rise in popularity of streaming services, legally and financially, there doesn't seem to be much will to help a shrinking segment of the customer base with a niche concern.

How much to charge for this would be a terrible debate, as trying to do it "at cost" per purchase - presumably the company's preference - would be heinously expensive.

I highly recommend https://libro.fm/ as an alternative.