It all depends on the kind of casino company you're dealing with. Some of the new casino companies does request for the KYC in their bids to deny their customers payment after winning huge amount of money while long existing and popular casino companies do ask for KYC so they can verify the customer wether he's the true account owner or an an imposter. For the long existing casino companies, I think it shouldn't be a big deal to provide them with all requested documents that'll prove you to be legally fit enough to claim your winnings
Going buy you comment I think it's safer and better to work with the long existing casinos who have been in existence for long time and have got good reputation enough to be trusted because they are most likely not to deny their customers wining on the ground of KYC which has not been done or completed as they are done mostly at registration or not even requested at all.
I agree with you if it comes to the long existing and reputable casinos, if for any reason they requested KYC, the requested document should be provided them as legal actions can be taken against them in case where things goes otherwise, but if it's with these new companies who are yet to get the required reputation they could possibly make away with customers funds and probably get away with it.