It really just rest on his judgement. While many of us are not open to submitting a single document about ourselves to a casino, many are willing to. Especially when lies upon it is the withdrawal their winnings. Countless threads so far expressing their disappointment after finding they are at the mercy. If they are not sending KYC documents, nothing can be done be regretting why they deposit in the first place. Casino being a legitimate with license still will help lure users to deposit but this isn't what OP was talking about.
Yes, decisions are made on an individual basis. But there are some consequences of these decisions that completely change your ability to play. For example, as I said, regulation and taxes worsen the conditions for the player. That is, for example, imagine that you are betting on an event with odds of 1.6, while in unregulated bookmakers you can bet on the same event with odds of 1.8. Obviously, by betting with the worst odds, you will quickly lose and will not have a chance to beat the bookmaker.