Well, I am convinced that sometimes "very reputable sources" can hear a story of "someone got booted", and pass it on. They can be quite sincere and reputable. It's the psychology of "everyone believes bad news, not good news".
Example of this psychology: If I came to you and said that our good friend Bob "just got arrested for soliciting an under age cop decoy in a child sex sting", you'd be saying : "Really ? That's horrible. How could Bob do such a thing
" But if I came to you and said "Hey, our friend Bob just won the million dollar lottery", you'd say "No way, that can't possibly be true". See how that works ? So too is it with md'ing: No one hears or registers the ability to detect at any place (they never give it a 2nd thought, nor would you question it). But the moment someone comes up and says "you can't detect at such & such", THEN you assume it's true, w/o question.
And suppose for a moment that it WAS true that someone got scrammed or booted. I got news for you: I do not consider such events to necessarily constitute gospel law. I do not necessarily consider them to mean "md'ing not allowed there".
Because I have seen SCORES of such happenings that ... turned out ... were nothing more than isolated flukes. Eg.: a ranger having a bad hair day. Or a cop who was merely responding to a call-out from a lady who thought you were bothering earthworms (and the cop has to justify his being called out, so he says scram). Or perhaps no one on earth besides that single authority cares, and it was just a fluke that he happened to be out and about that day.
I have lots of parks where either myself, or someone I've heard of, has received a scram. And ... sure ... you give lip service at the time and comply. Yet years later, we look around among our ranks, and no one's ever heard so much as "boo" since then. Thus I do not necessarily construe stories of supposed "scrams" to constitute gospel law going forward. Sometimes it just means: "Avoid that one individual".