I only had only one college professor enforce this ordeal of purchasing textbook with single use code. This was about 10 years ago, and recall being broke, and the book costing over $200 out of pocket... for a mediocre course textbook, and crappy online content that didnt hold its value to all that extra cost.

All of the homework and tests were done with the online platform, which helps from wasting paper ....although, the larger benefit is all of it was more for the professor, having portal access and ease of grading assignments, making their job easier, at no additional expense to them because the students (mostly poor) shouldered all of the costs instead....on top of paying for the college course tuition and fees, which part pays the professors salary.

Its disturbing that this is still commonplace, and FTC hasn't done anything about it.