> natural logistical limitations for copying and improvement.
There's also a marginal cost beyond the first unit, whereas for software, there is none.
> I cannot OCR a paper book I own, make modifications to it and then publish it on the web.
You'd be violating a copyright, which is a separate point of discussion, but I'm talking about the physical book itself. You've sold me a bunch of paper bound together, and I'm allowed to modify (or destroy) it, as well as resell it to someone else.
I cannot OCR a paper book I own, make modifications to it and then publish it on the web. Nor can I photocopy that book and give it to friends.