Here's what I would say to this link :
1)
Consider the source. A purist archie publication. WELL OF COURSE they hate md'rs. And will spin anything/everything to be "dire". What did we expect from their side of the aisle ?
2) Notice they do not go any further with their assertion that : " ...In France, hobbyists using metal detectors is against the law. ..." They just drop that there. AS IF IT'S A DEFAULT GIVEN PREMISE ! They cite no law or rule that says such a thing.
And if you hover your mouse over the word "metal detector" there, you'll see it can take you to another link. Once you go to that other link, you see it has nothing to do with France. Huh ??
3) Whatever laws/rules this archie source *might* be relying on to substantiate their claim (that md'ing in France is "against the law") could be laws applying to public lands. Not private lands.
4) And notice that EVEN AFTER THE ASSERTION, that it goes on to say that you must turn over "artifacts of cultural heritage" to the state. Eh ? Ok, fine, so detect, but that you just have to "turn over items to the state", eh ? And again, this might only be for public lands in the first place. Gee, I could say the same thing about the USA too . We have laws that forbid "harvest" and "remove". That cover every speck of public land as well .
5) And let's be totally serious here folks : Did you notice the sheer amount of coins and treasure-stuff involved ?
This guy was not a casual coin-hunter, with a few coins to sell on ebay. He had over 27k artifacts and coins. Valued at nearly a million $$ . And he goes waltzing into govt. officials, trying to get some sort of green light ? !!! ?
Why not just sell the cotton picking things , a few at a time, on ebay or whatever ? Eg.: You can go on ebay RIGHT NOW and see ancient coins going back and forth between buyers/sellers/collectors ALL THE TIME. From EVERY COUNTRY. Since when isn't coin-collecting an age old hobby ?
In other words, I do not think that the guy in this article is the brightest bulb in the box.
6) Everything in this article could be said of the USA and the UK too. ANYONE can make a total nuisance of themselves, parade themselves in front of purist archies, and be made some sort of example of.
Eg.: I could find some purist USA archie to cite supposed laws in the USA too (ARPA), and then follow it with some story of someone getting "roughed up" for tromping around at Shiloh or Gettysburg.