farscaspe, I have often said that there are a lot of parks, schools, etc... where no one cares, UNTIL you ask. Ie.: you get a "no", where, quite frankly, no one would ever cared or noticed, till you brought the "pressing issue" to their attention (and we all know what the easy answer is).
You situation now brings truth to "No one cares, till you fight it". Ie.: the matter might have gone away, in your city, had you just avoided *just* this one woman, or *just* this one park, etc.... for awhile perhaps.
Here's a true story to illustrate this:
A fellow in a midwestern state got booted from a particular state park, where he had never had a problem before. When he asked the ranger "why?", the ranger would only say "because it's not allowed". Any attempt to ask "where's that written?" seemed to be starting an argument, so the md'r just left. Once he got home, he researched the matter, and found that ..... in fact .... there was no specific prohibition of metal detecting in his state parks, barring something silly to morph to apply to it (cultural heritage wording, etc...). Thus, he felt he had been arbitrarily booted, and felt like he should fight it, video-tape it, etc.. But in the course of his research into his state's laws, he found out, coincidentally, that the neighboring state had verbage that actually ALLOWED detecting in their state parks (albeit perhaps only on sandy beaches, non-historic monuments, etc...).
The md'r thought "wouldn't it be cool if our own state had such clarifications and wording, so that individual rangers weren't left up to their capricious whims and interpretations?!" So he set about letter writing to the highest-up dept. managers in his state's park's dept, objecting to his booting, and suggesting that they implement wording similar to the neighboring state, etc... And he got solidarity amongst his club members and others in the state to rally to object to his booting, and press for clarifications, etc...
Weeks went by, and he got no response from the state capitol. Finally, a month or two later, while still awaiting a reply, the md'r happened to be metal detecting in ANOTHER state park, that he had never had a problem at. But THIS time, he got booted, by a ranger he had seen before, who had never cared. So he asked the ranger "but why? since when? etc...". The ranger pulls a paper from his pocket, to show the md'r. It was a department memo xerox that had just come down from state capitol, to all the individual parks, to "be on the lookout for metal detectors, as this activity is not allowed" blah blah blah. And when the md'r looked at what this ranger was showing him, guess who it was signed by?? The VERY same high-up bureaucrat whom the md'r had been petitioning for clarifications, sanction, etc.....!
The connection was obvious: the person in state capitol must've gotten all the letters and petitions, looked into the matter, and sent out this memo, effectively creating a new rule. The md'r couldn't help but think that he should have left good enough alone at the first park, and just avoided just that one park, or one ranger. Even his fellow hobbyists in that state, when they got word of this (that now state parks were off-limits), felt he had stirred a hornets nest, that would have been better left alone.
So guys, we need to be careful about this solidarity, fighting thing. Sometimes it's better just to use a little discretion, go at off times when busy-bodies aren't around, etc....