Ray2, the answer you got, where a desk-bound bureaucrat twists some related verbage, to apply to your "pressing question", is not uncommon. It happens all the time in places where detecting is not a problem, and no one ever cared before. For example: In my own city, the town's main park was simply routinely detected, and no one ever had a problem before. Yup, in broad-daylight, in front of passing traffic, landscapers, etc.... No one cared. And those of us who hunted it, never had any reason to suspect otherwise, to begin with. Then one day a newbie "takes it upon himself" to waltz in to city hall, and ask "can I metal detect?". I guess the desk-clerk there took his question to various other city employees, and they figured his request would run afoul of "collecting" verbage or "defacement" verbage, or harming earthworms .... or who knows what? So they told him "no".
Because think of it Ray: The mere fact that you, or someone, is standing there asking "can I?" simply implies that something is inherently wrong (damaging, or evil, or whatever) with you or your hobby, that you to ASK, to begin with! (Lest why would you be asking, if it were innocuous?). For example: would you have asked to fly a frisbee? So with this implication in mind, it practically dictates your own answer. And the sad part is, perhaps no one would ever have cared, or even paid attention to you, unless you were being a nuisance in some other way.
Heck, it's as colonial dude says: Is anyone really looking over your shoulder doing the math on the age of coins you find, to begin with?