garyo1954. Good answer. You say the county personell's objection to md'ing could be:
a) holes that create a possible trip hazzard (and not "cosmetics" in forest like that). Or
b) the aspect of "taking" or "harvesting" or "collecting", via the old addage of "if everybody took one pretty rock home, then pretty soon, the beach or forest or whatever, is no longer pretty.
And I agree. Both of these reasons could be reason to forbid detecting, if some desk-bound bureaucrat thought about it long enough and hard enough. Sure, such things could be applied to the question of "should we allow detecting?". But it still doesn't answer the question of: why was this question even on their plate, to begin with?
And so too might it have been an answer of "historicity" (aka cultural heritage, etc...). That seems to be fairly clear in some emails exchanged from Cook county authorities, and md'rs on the subject. I can't find the link right now, but perhaps someone can find it and link it here? The context of the email exchanges from the comissioners, at least at first, made it clear that it only concerned historic spots in the forest, "not all cook county land". So you can therefore add a possible option (c) to the above list of possible reasons detecting was banned.
But all this still fails to answer the question of: Why did any of THOSE reasons "come on their radar" as something that needs to be addressed? I mean, what brought this up to them? Any such reasons can be a reason for any beach, park, school, etc... to enact a law or rule, afterall. Yet as we know, there's no shortage of public places where no one thinks of such silly things. So why did it become a vote or decision-needed-issue here?
The reason I needle at this, is I suspect I know the answer: If the evolution of this particular case could be un-veiled, I have no doubt, that the reason it "came up for review" or "got a new rule" and so forth, was that someone must've gone in asking cook county "can I metal detect?". THAT is what probably got it on their radar as a "pressing issue that needs to be addressed", and NOT the (a), (b), or (c) above, even though, sure, in-the-end, as something to refer to as their reason for their "no", it's their go-to reason for the rule they just invented.