80 000 hours books give-away - ebooks

[First post.]

In the recent 80 000 hours podcast (https://80000hours.org/podcast/episodes/will-macaskill-ambition-longtermism-mental-health/), it was mentioned that new newsletter subscribers may choose a book to receive for free.

I wondered why there is not an option to choose an ebook instead of the printed version. (Was not able to choose that option when I signed in a few months back. As I had bought the Precipice before that, I chose none.) It would be in fact the more cost-effective way to deliver the same information.

More generally - if you are giving the books away, i.e. you are not interested in the royalties, why are not the books available for free download (eg. after some embargo to ensure the publishers' profits)?