A "No girls allowed" sign on a treehouse might, if the person putting the sign up had ownership rights, be enforceable against those who violate the sign as being trespassers though.
Robots.txt does serve as a kind of "no trespassing" sign, and it'd be interesting to see how it holds up in court in terms of serving as commonly recognized notice of limitations on permission to access a service, for automated systems. Quite often just putting someone on notice that they're not allowed to access something is sufficient to turn it into a crime, and robots.txt is how the internet community puts automated agents on notice.
I agree with you generally, except that this would incentivise, for lack of a better term, "copyright assassination" - the deliberate termination of someone in order to release lucrative copyright.
A reasonable amount of time (a decade or less) after an author's passing should mitigate this for the most part, or tie copyright to expected lifespan (eg, "100 years after the author's birth")
This wouldn't apply to corporate-owned copyrights, of course. A hard time limit should be fine there because the interest in the copyright would always pass to someone
They destroy the used market by bundling in online codes which are not available separately at a reasonable cost.
Those codes are presumably for the online test portals etc? If so, the problem is universities outsourcing their testing and scoring to the textbook providers.
They come out with new editions every few years with marginal changes. You can't ask students to buy an out-of-print edition as a practical matter.
You can specify "any edition" or a range of acceptable editions. Universities and schools alike once had thriving secondhand textbook markets, there's no reason (save for the aforementioned outsourcing) that there couldn't be again.
For starters, ChatGPT is not a deterministic system.
Sort of. If you control enough variables it can be. It's as deterministic as a PRNG would be. To get truly nondeterministic behaviour you have to bring random input in from external sources.
If you aren't rich you should always look useful. -- Louis-Ferdinand Celine