The age limit placed on people below 18 year to keep them away frim gambling have not been most effective as we have hard records of under age gambling in many place and this is a pointer that casino has indeed misolaced their primary responsibility which is to prevent that from happening and that is why there is need for KYC.
Casinos have provided regulations by not allowing underage children to gamble. And even though casinos have implemented KYC for their members, that can't stop minors from registering and gambling. They can do KYC using the identity of adults around them, which helps them gamble. Perhaps, this can be reduced if each parent pays more attention to supervising their children using devices connected to the internet so that their children do not visit casinos.