Casinos will always ask for KYC information from their players when I they find out that one of their players is either cheating nor trying to do money laundering. Truly must casinos that are genuine at offering no KYC services for gamblers are actually good at what they do and will not ask for verification from players except they suspected that something is wrong.
There are only few casinos that provide this kind of service for gamblers and majority will ask for KYC verification for their users.
If casinos suspect anything like cheating from their customers they can decide to ask for kyc if they have not asked that before but in a situation where they have all the details of the customers and they still do not want the customers to to have access to their accounts it becomes a problem. In the casse of money laundering, the casinos have the right to investigate the account of the customers to ensure they do not use them to launder money which could be a big problem to them but where there is no issues it becomes a bad decision to the casino if they decide to ask for kyc when they are a non kyc casinos but they do this to withhold the winning of the customers.