I hope you read more of the article than the first paragraph and realized they were not at an archeological site and did not steal any arrowheads, they were merely looking for them as a father and son hobby. No arrowheads were found, but the act of merely looking is criminal, which they were not aware of.
I value your contribution to this discussion, but you might have missed this part of the article: "Wendy Olson, the U.S. Attorney for Idaho, said the men were on an archeological site that was 13,000 years old. "Folks do need to pay attention to where they are," she said."
Thanks for pointing that out, it's a reasonable concern. That is indeed the US Attorney's argument.
Just to clarify, it is not necessary to be on a recognized archeological site to be illegal, intending to collect artifacts on federal land is a crime whether a recognized archeological site or not.
But in this case they were in camping in "Salmon River Canyon, near the mouth of Graves Creek, which is in Idaho County" on land "administered by the Bureau of Land Management".
It's not a recognized archaeological site beyond the interpretation that every location in the US is an archaeological site.
To be sure, there are arrowheads and/or evidence of human habitation on nearly every square mile of this continent. Just having the possibility of arrowheads doesn't make something a real archaeological site unless we bend the definition so far as to not have any meaning.
