The simple truth is that fraud detection costs casinos a lot of time and effort. They are not inclined to give away their secrets on how they go about their business. That's just a fact and IMO perfectly understandable.
So what happens when we, for instance, take them a case and ask to see the proof backing their decision? If they know or suspect that we are going to hand the proof over to the player they simply won't give it to us. Full stop.
If however we give our word that the evidence remains confidential -- as we have for many years and continue to do so -- then maybe, MAYBE, the casino will trust us and shown us what they've got.
Wouldn't the solution be rather simple?
Player makes complaint to ADR after getting nowhere with Casinos own support.
Require UKGC licensed Casinos to work with all UKGC licensed ADRs as part of their own licensing conditions.
Casino provides their side of the story along with supporting evidence.
ADR is not allowed to disclose evidence to player in cases of player fraud.
Player has opportunity to make complaint about ADR and have the evidence reviewed by a second set of eyes at the UKGC.
Or maybe I'm just too far removed from the overcomplicated thinking of political busybodies