I agree in terms of the economics of it for many readers at least. I buy a lot of books. I would buy a lot more e-books I think if prices were reasonable i.e sub $5, vs. usually being as much a print copy. I also gift many books. I recently downloaded 200+ books via b-ok.org...most of which I certainly wouldn't have bought and probably half of which I won't open for years if ever. Two months later, though, a couple of the books I enjoyed that I've ordered new copies to be sent as gifts as friends.

I would be a good candidate for something like Kindle Unlimited, but most of the books I'm interested in aren't available there. At least half the books I downloaded (many academic as well as poetry and other books) are not available on Kindle Unlimited.

Subscription music aggregators seem to have a pretty decently comprehensive offering in a way that the book, news, and movie aggregators don't.

It would be a little weird, but if there was an app where I could read any book but every 20th page or so was some full page ad...I could live with that (as long as it wasn't a video or something). Not sure if that kind of a model could work in terms of the economics for writers -- but it's of course working for news mostly and for some film sites like Tubi and Pluto.