Let's assume ebooks are 20% (I know that's the upper bound you're positing, but let's start with that). If my salary were reduced by 20%, I would definitely say that I was making "much less". Would I say the same if my salary were reduced by, say, 10% rather than 20%? Maybe, maybe not, but I doubt I'd go so far as to say that characterization was simply "not accurate".
I think it's fair to say that eBooks haven't revolutionized the way the majority of people read books to anything like the degree that was expected (or has happened with music and video).
