To be honest I believe no casino will make such rules without including them in their terms of agreement however it is so unfortunate that most users fail to read those terms and conditions.
KYC still is something every internet user should try to avoid at all costs due to the risk it exposes users to.
All casino has several tricks to cheat the gamblers. KYC is just one of them. Several days ago the casino stole may prize. They said that it was a technical mistake and returned my bet without all the other money.
So the house always win. They always have something in ToS that allows them not to pay.