I think the practical difference is that the rates that publishers charge libraries for ebooks are significantly higher than what either consumers pay for the ebook or what a physical book costs. See https://archive.is/Ha3VQ for one example:

> To illustrate the economics of e-book lending, the N.Y.P.L. sent me its January, 2021, figures for “A Promised Land,” the memoir by Barack Obama that had been published a few months earlier by Penguin Random House. At that point, the library system had purchased three hundred and ten perpetual audiobook licenses at ninety-five dollars each, for a total of $29,450, and had bought six hundred and thirty-nine one- and two-year licenses for the e-book, for a total of $22,512. Taken together, these digital rights cost about as much as three thousand copies of the consumer e-book, which sells for about eighteen dollars per copy. As of August, 2021, the library has spent less than ten thousand dollars on two hundred and twenty-six copies of the hardcover edition, which has a list price of forty-five dollars but sells for $23.23 on Amazon. A few thousand people had checked out digital copies in the book’s first three months, and thousands more were on the waiting list. (Several librarians told me that they monitor hold requests, including for books that have not yet been released, to decide how many licenses to acquire.)

The difference is that the books value, even reprints, become lower over time. Until they hit a minimum margin for the construction of said book.

Digital books/content requires little to no cost to replicate, unlike printing new books. But we have seen that the price of that content follows the "physical goods" model. Why should a 30-40 year old movie cost you $20 to steam?

The difference it's that in the physical case the choice is up to the library, in the other it's forced upon them by the publisher.

> Is there really a meaningful distinction between how libraries treat digital book licenses and physical books when you actually hit reality?

The main difference I see is the centralisation of censorship vectors. Pulling physical books off library shelves is visible and rightfully prompts a shitshow. Bullying a publisher into not renewing lending licenses strikes me as way easier to pull off.

They sell them at the end of their life, sometimes, so you recoup a bit of the cost there. And you can also get books donated which reduces the up front cost.

I don't see a good way to do that for digital copies, and of course the expiry would be wholly artificial scarcity for them even if it was only a little bit more expensive than physical.

1) library has control of the decision-making; 2) they can resell or donate the book when it's exhausted its shelf-life