Anytime there is a "no" passed out, or talk of a "ban", or an actual "ban", YOU CAN BE SURE that the reason ALWAYS cited will be "holes". So the md'r mutters under his breath : "Durned those md'rs who must've left holes". Right ?
But don't be so quick to assume that someone left holes, leading to this ban. Even with a supposed "... complaints we received" as cited in this article. Because often-time the old addage of "holes" is merely the "GO TO" reason to justify a decision or law they just made. EVEN IF THEY NEVER SAW ANY HOLES.
Here's what I'm talking about: If you were to ask the average non-md'r "what do you think of, if/when you see an md'r in the park ?". They will immediately conjur up images of a guy who's going to dig, right ? Ie.: "holes". EVEN if you leave no trace, and/or even if you didn't even ever stoop down to dig while they watched you, it's STILL just the knee-jerk mental connotation of a "man with a metal detector".
That's why when person's have gone into city halls asking "can I metal detect?", they will often get the answer "no, because of holes". So the md'r naturally assumes "aha, someone must've left holes in the past". But I'm not so sure that is necessarily the case. It is often just the go-to reaction answer. Because let's face it: No one in authority is going to say "Let's ban this just to be mean, and for no good reason, simply because we felt like it". NOoooo. Instead they will always say "no [or "ban"] because of 'holes' ", even if no one can cite such an incident.
Like those supposed complaints that supposedly the city got (leading to this ban): If that's even true, then consider that those "nosy-parkers" might simply have seen a man with a detector, and just ASSUMED (because of the connotation, or seeing him with a lesche, etc....). Or perhaps they saw him digging, yet he filled his hole and left no trace. Well that doesn't stop the nosy parker from ASSUMING he's about to leave it un-covered.
Hence don't be quick to assume "holes" were ever at play in this article. Maybe, but maybe not.
As for the idea of "permits", I will address that under diggervance's post.