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.
Underage players can indeed use their parents' IDs to verify their accounts. That's why parents need to be able to keep up with what's happening with technology so they can check the site if their children later borrow their parents' ID for verification. Parents can also know what their children are doing so they can understand that the site is not for children.
Yes, by doing KYC, we can prove ownership of our account when it is hacked or there is an activity we did not do. The casino will know that we never do that so the casino will not take action such as freezing our account for further investigation.