I have had uni professors sign books to make sure people actually bought new books and not used ones (he wrote them); unfortunately for him i had access to toluene to get pen ink off; did the same to all of my peers;
Fuck those kind of professors
He threatened you to either buy a new book or he would make your uni career hell, one of my mates did it, at the last exam he sent him back 5 times, the last time he went to take the exam the coordiator said "what else have you got to ask to him; he told you everything in your course; [insert name] give me the paper" he signed the paper and sent him off; the prof. Still gave him only 60/100.
I still want to slap that piece of shit.
After that i taught other people in the uni to do that; he tried to mitigate by writing over the printed title of the book; hoping that any tampering would be evident; toluene didn't touch the toner, so it didn't work
Here in italy no one gives a quater of a fuck about that kind of shit.
Good thing is that the same can be said when after the last exams he always needs to call a tow truck since he won't have tires, not even cameras were able to stop them, and i'm quite sure other professors turn a blind eye to them since they also hate him.
just fyi:
"teach" is one of those words in English that has a different suffix for it's past-tense: it is "taught".
Eg. "They taught me to sew."
"teached" is improper.
Note: not to be confused with "taut" which is pronounced the same.
Side note: to anyone looking to follow this method, please try to limit the amount of toluene you are exposed to by wearing gloves and working in a well ventilated space. It can do dirty shit to your nervous system and I've seen chemists start to experience symptoms from relatively little exposure to the fumes.
In general if you can get a respirator or at least an n95 mask if you still have them from covid(apparently that doesnt work); also make tries on an old book before going on the good one, at least if you mess up it isn't another hole punched in your wallet
A respirator with an organic vapor trap will work, but an N95 will do essentially nothing for chemical vapors besides give you a false sense of safety.
If you have nothing, do your work outside and don't work with your face directly over areas with the toluene.
You know what I also hate? When professors take your phone while in class. I had a professor that did that back in my days of gender studies college and he saw nudes of my they/them girlfriend at the time. Mannn it was an awkward rest of the class and he didn't tell anyone, but I really showed him, ended up taking the day off next day and nailed his wife. Dude never found out or anything, turns out her wife has had countless orgies with several other guys while he's busy at school teaching students. Still never confirmed whether he found out or not.
Overall, lost my train of thought, in response to your comment they do it to be sure you have the most recent information in the book, don't see an issue tbh.
The specific case here was the professor had a financial stake in new books being sold.
I do agree updated editions with new information could be important, but again when theres a financial incentive to sell new books, the obvious lean will be towards making new versions even if there is no new information.
Since the books can be required, they should be required to show proof they have substantially added to their edition or else relegate it to a minor revision (maybe adding sub-editions like 1.0, 1.1, 1.2; where you only need the first number to be current). Right now its a whole lot of, "Trust us you need this book and the only pre-owned versions are out of date".
As a side thought, this is the kind of thing that makes me wonder if they use the book costs to weed out those that will not allow themselves to be abused to that degree. This would leave only those who would conform to their leader/manager/teacher and are less likely to try to change the system.