perdidogringo, I'm not from Europe, nor have I detected there yet, but I hope I can chime in on your post anyhow

My sister married a French emigrant, and they go back to France and Italy every few years . So I've spoken to him at length about someday tagging along on one of their trips, so I can detect. Thus I've studied this subject too. That, plus just generally being intrigued about md'ing versus laws anyhow, haha
The answer to your question will be based on definitions of lots of your terms. The knee-jerk pat answer will, of course, be the UK is the most relaxed. But that could simply be an "image" thing, simply because there's so many hobbyists there. And because of the odd system where the crown "buys" your stuff, if it's an astounding cache, or something super historic . Which, BTW, is a much mis-understood system! Yet it makes people from other countries think there's some sort of love-affair with archies and md'rs there. Or that there's "cart-blanche" to detect nilly-willy anywhere there. But this is not true. Because notice that UK hunters are doing 98% of their hunting on private farmer's land. Well gee, you can do that ANYWHERE in the world almost , eh ? Thus those UK hunters DO INDEED have scores of public land where they can't just waltz out to (just like the USA sensitive historic federal sites, for instance).
And if you start to explore all the other European countries laws, on commonly cited compendium lists that circulate on the net, you can come away with dire-sounding verbage that, at first glance, makes it appear to be a big no-no in those countries. Oddly however, there's no shortage of md'rs in some of those countries, who have no problem at all finding places to hunt.
So you might ask "how can there be md'rs there, in-light of what I read on this compendium list?" The answer to that comes from asking yourself how such compendium lists EVEN CAME INTO BEING, to begin with. Someone , way-back-when, either went and asked . Hey, who better to ask than the countries themselves, eh ? Call up or send an email to an archie there asking "can we metal detect?" or "what are the laws regarding md'ing in your country?", etc.... Or perhaps the person compiling the list looked things up for themselves, or copied and pasted what other before them had found, right ?
And no doubt, in all those countries, way predating metal detectors, there was cultural heritage laws . No different than the USA's ARPA, and the UK, etc.... So that, of course, no one thinks he can pillage historic monuments. And JUST LIKE ARPA, will sound "dire". And sure, if you ask enough purist archies: "Does this mean no detecting?", they will of course spew more such dire warnings. All these things make it onto the wonderful compendiums, and ... how can you argue with that ?
The same thing happened way back when, when the state-by-state list of the USA's state parks was attempted: Many of them had dire sounding "no's". Or odd ball stuff about "with permission from each kiosk" (although that was no where written in actual park rules). And when these lists came out, you had old-timers scratching their heads saying "since when?". See how that works ? Someone in the bureaucracy answering the "pressing question" with the "safe answer". And pretty soon, it just BECOMES the defacto new law or policy when truth was, it was never an issue prior to that (assuming you weren't raiding obvious historic sensitive monuments).
One thing that the European compendiums don't take into account (isn't spelled out either way to the casual reader) is that they would deal with PUBLIC land. They're public laws afterall. Yet what a farmer does on his own property is for him to decide. So private land (just like the UK) is outside the scope of whatever dire things you're reading. But the compendiums make no distinction, so the reader is left to assume it's border to border everywhere.
Also notice that whatever you're reading on those compendiums are frequently citing "historical" and "antiquities", etc.... Thus applying to OLD stuff, not new stuff . And bear in mind that "old" in some of those countries isn't "old" till you're talking 500+ yrs. old ! But again, the lists make no distinctions, as someone answering the 'pressing question' just lumps everything into one easy answer.
I sold a detector to someone on ebay, who'd won the bid from one of the countries there with the most dire sounding laws on that list. So in the course of communication getting ready to ship him the detector, I couldn't help but ask "how can you detect there?" (and I sent the link to the compendium). He answered back that it doesn't apply to private farmer's fields. And/or that, quite frankly, they are so far back in the woods, there's no one around in the first place.
I could go on and on about this subject (a bee in my bonnet) but this is all for now