In short, it sounds like the answer to the "why" question at the top of this thread (https://news.ycombinator.com/item?id=41447904) is: the scan is a derivative and copyright law lets you lend books, not derivative works thereof

Which seems like a nitpicky distinction to me when it's the same words on the same page and they're not shown to anyone else at the same time... but such is a judge's job as opposed to a legislator