I've bought a few albums from Amazon recently because they offer their AutoRip service. That means that as soon as I've paid for it I can download an MP3 version. This combination of immediacy and tangibility (is that a word?) suits me well. If I like something enough to buy it I want to hold it as well. Otherwise I'll just access it via Spotify or You Tube.
I wish the book trade would do something similar. If you pay £20 for a book you want to start reading it straightaway and you also don't want to haul it around on the Tube with you. You also need to increase the number of opportunities you have to read it. It would work for me and would work for the publishers. We'd read more quickly, probably find the reading experience more satisfactory as a consequence and buy more books.
How they do it I don't know. It can't be beyond the wit of the trade.