All books have DRM like features:
1) Generally a book can only be read by one person at a time. Sure people can share a book but rarely do you see two or more people reading a book.
2) When read aloud a book can only be heard by the people in the room.
3) Copyright doesn’t allow a book to be translated to other formats. I cannot read or scan a book then post an MP3 or PDF of it without permission.
4) If I give a book to somebody else, I no longer have access to the book.
5) If my copy of a book is destroyed I have no rights to other copies.
6) No warrantee or replacement. If a book is damaged by myself or other forces the publisher or author isn’t responsible for replacing my book.
7) If I lose my book I am not entitled to a repalcement.
8) When playing “book club” everyone has to have the book.
9) Books do not have to stay “in print” and are subject to varied availability. For example search for Stay up Late by David Byrne