Little-known fact that shows just how enlightened ORA is: you can go to https://members.oreilly.com/account/benefits, and buy any ebook upgrade from a physical book for $4.99.
They don't even check--they just take your word for it.
I just hope people don't abuse it, but, as Tim says, they'd rather have 100K books floating around and 10K books sold, than just 10K books sold. Can't help but improve their visibility and overall sales.
Good folks.