[Xxfireman]

Yes, this is how textbook manufactures sell to university. One time codes for online exercises / labs. This happens mostly for intro classes. I have no idea why universities do this, my guess is they are sold on hw problems being randomized so it makes cheating more difficult.

[eesmith]

What I don't get is that 20 or so years ago there were professors writing online books meant as no-cost alternatives to the corporate publishing companies which controlled much of the academic market.

Why did all of those projects fail?