What we do need are honest amateurs out there doing this, but the honesty does sadly need thrusting upon some of them.
What person, in their right mind, is goint to 'volunteer' for a job like that? Talk about putting your head in the lions mouth....LOL.
I think, in principle, your idea has merit. It would certainly put an end to the activities of those detectorists who raid sites for the purpose of finding saleable items.