Hey there.
To be honest, this is a common misinterpretation of the fair concept. The shopkeeper example is also imprecise because the rules you accepted when registering your account at the casino specified which countries were prohibited. I would say that there is no such agreement if someone goes to buy cigarettes.
As stated in the complaint, ideally you would not even be able to visit the website. Furthermore, the casino was unaware of your origins because the verification is the only method used to confirm a player's country of residence.
We acknowledge that this is a very negative user experience, but we cannot hold the casino accountable for it. Most players who feel they should be compensated for what they have rightfully lost typically seek legal advice. To be honest, our stance does not support the idea of retroactively refunding losses in these situations because that would be unfair to other players and it also supports the idea that playing without the risk of losing is not conducive to safer gambling habits.
I can see why your viewpoint is different from ours, though. I am not sure if an honest explanation could make that different.