Hm. I agree online textbooks are different because you're not just paying for the textbook, you're also paying a school tuition, and the school isn't going to refund your tuition just because the textbook provider made a mistake.

I asked another poster just upthread about the software (such as Creative Cloud) case.

You can buy text books outside of school. Let's say I buy some OReilly or Manning e-books, and then they take them away from me. Whereas the physical copy for just a little bit extra remains mine for as long as the copy stays readable (centuries if given care)