Why don’t books come with a digital version?

I’m reading a book. It’s a wonderful book: Salman Rushdie’s memoir ‘Joseph Anton.’ And the thing itself is beautiful: well-printed and bound with a vellum-feel to the cover underneath the dust-jacket. Just look at it. It’s just the sort of book you’d want to own, to cherish and to keep for the rest of your … More Why don’t books come with a digital version?