So everyone should be permitted to take what ever they want? Insane. Don't get me started.
Take only pictures...leave only footprints.
Just because you don't agree with another country's laws doesn't mean that you don't have to respect them.
Take a look in the mirror first. Your own country has some rules, regulations and laws that are beyond belief, but anyone visiting the U.S. has to abide by them, no matter how nutty they are.
Think about that the next time you have to take your shoes off when going through U.S. security. Or when they confiscate your Swiss army knife with the 1 inch blade, but let you keep your manicure scissors and your 6 inch long stick pen. And then give you real cutlery in first class. Or when they confiscate your unopened, sealed jar of Skippy peanut butter (yes, it happened to me). Not sure how that qualified as a liquid, gel or aerosol. Clearly it was a WMD. Nutty. But, everyone has to abide by the rules.
And you don't think the U.S. has rules about removing things from beaches and national parks? Think again:
"On lands administered by the National Park Service, it is unlawful to excavate, remove, disturb, deface or destroy any historic or prehistoric building, structure, ruin, site, or in-place exhibit, artifact or object, or to collect, appropriate, excavate, damage, disturb or destroy artifacts, pictographs, petroglyphs, objects of antiquity, fossils or scientific specimens (16 U.S.C. 470ee, 16 U.S.C. 433, 36 C.F.R. 2.1, 43 C.F.R. Part 3)."
Try taking lava rock out of Hawaii. Good luck. What's the problem? It's just rock - right? There's lots more - right? I'd love to see you try that argument with the TSA.
You're actually quite fortunate. You could have been arrested and fined. They gave you a break.
I guess you did get me started.