A useful rule that I came across a while ago is "ask yourself before doing something (such as picking a flower in the wild), what would happen if a 100 other people did the same thing?". The answer should usually be "don't do that thing"
A friend, college educated responsible adult, went to the petrified forest in Arizona. Park ranger gave the whole talk about how rare and special these rocks are, and how they're disappearing because people are stealing them. The ranger indicated there might not be a park in the future, because so much is going missing. She had an immediate impulse to steal a rock. She claims she didn't act on it, and I believe her.
I think there's some inherit psychology that's tough to get around, some "I better grab one while I still can" deep down part of our reptile brain. People are still animals. Out on vacation they may not be fully engaging their critical thinking skills.
FWIW, Jim Gray's Petrified Wood Company has a vast supply of this stuff you can buy and take home. It's right down the road in Holbrook. Very interesting store even if you're not planning to buy anything. (No working website that I could find. Google it. I have no connection with them.)
I have a lot of flowers that grow out front of my house. If you pick my tulips, daffodils, roses, or lillies then I'll be mad because they're pretty, short-lived, and for pollinators. I go to great lengths to have blooming flowers almost year round and a great deal of planning goes into that. One flower dying prematurely or going missing isn't a big deal, but if everyone picked a flower then the great deal of pollinators my property attracts would be impacted in some small way each time, and the pollinators play a key role in the micro-ecosystem of my yard. I do my best not to disturb them. If you rip up the bulbs for your own I'll be doubly mad because you're just selfish at that point. Go buy your own bulbs like I did, or better yet foster a yard where bulbs multiply.
On the other hand, nature isn't so delicate. My ground cover has smaller blooms most the year and provide the pollinators with much more abundance and resiliency to what people or animal might do to my "prettier" flowers. It's difference between O(n) impact to O(log n) impact.
Sorry to be pedantic, but the categorical imperative is not about reasoning from the consequences of an action if everyone did it. It's about testing whether it's even possible for you to will the maxim of your action as a universal law without contradiction, or to what extent your action respects the rational agency of other humans. You could make the Kant-inspired argument that taking a limited resource for your private enjoyment does deprive others of their agency, but it's not Kantian to say "it's wrong to take the fossils because then there will be no more fossils."
I guess it would've been more honest to say "sorry to seem pedantic," because for me the comment was not mere pedantry (which I think of as hairsplitting for the sake of hairsplitting) but rather a matter of a fundamental distinction in moral philosophy (consequentialist vs. deontological ethics).
I mean, philosophy has a reputation for just that kind of hairsplitting but this seems to bear pretty directly on the basic ethical question of "What should I do?", one of the most important questions for humans to ask imo
