So too does that seem to be the case of the USA too, where layers of odd bureaucracies and interpretations bring about odd threads on this very matter! One guy detects state parks in his state, and never has a problem. While the NEXT guy in that VERY same state shutters at the notion, insisting you'll be immediately jailed, confiscated, etc... Or other such odd-ball answers from bureaucrats depending on who you ask, what mood their in, the mental image they have in regard to your question, etc.... But tell me LM: does this fact of odd and overlapping and sometimes confusing rules mean that: "Ergo, detecting the USA is bad internet advice, dangerous, etc..."? No, of course not. Last I checked there were lots of people detecting here w/o a problem in the USA (assuming they're not snooping around obvious historic monuments). So the fact of "confusing data" does not necessarily mean you can't do something.
You're right: those metal detector might indeed be sold for industrial business purposes, eh?
I have no doubt that if the OP writes enough letters to consulates, border bureaucrats, and lawyers, he will indeed find someone to say "absolutely not". So too would be the answer if you wrote letters to enough archie lawyer types here in the USA too. Because perhaps they're couching their answer in terms of shipwreck salvor laws (ala mel fisher legal hassles), or APRA, shiloh, lost & found laws, blah blah blah
There's the humorous story of how Fisher Co. did exactly what you suggested, when the question was posed to them about detecting in Mexico. How did they answer the question? By doing exactly as you say: They forwarded the question to a Mexican consulate, or some such govt. bureaucrat (hey, who better to ask than Mexico themselves, right?). And someone there told them "no". Even to the point of citing all sorts of scary things. But the odd thing is, that detectors are a common site down there in Mexico (on tourist beaches for example). And there are detector dealers in major cities there (INCLUDING FISHER DEALERS, doh!). So .... the old "no one cared till you asked" routine can happen on national scales too.
I'm not saying to break laws. By all means, if there really is a law that says "no metal detecting in Turkey" (that extends all the way down to private farmers land even), then by all means, keep it. But that doesn't seem to be the case here. If I'm wrong, then please link us to the law. And seriously now, do you really think those detectors are for finding nails in logs over there?