This not entirely true since underage player can always use ID of their parents to verify their account. I’ve done this before on exchange when I’m still underage and doesn’t have valid ID to verify my account. Some parents doesn’t care about KYC since they don’t know much online technology.
The only benefits of KYC for me is the ability to recover my account when it’s hacked since I can prove ownership using my ID that I use to verify my account.
That is a risk that will always exist as many parents are not really that knowledgeable about the current technology and they have been left behind by far by it, and as such a smart kid can use the information of their parents to create accounts in any casino they may want and gamble that way, and this is especially true if we are talking about cryptocurrencies, because when it comes to fiat then at least the parents could catch the kid by reading their bank statement, something not possible when a kid is using their own money which they have stored on their bitcoin wallet.