I still maintain my point that, the casino has a very huge role to play in the regulation of underaged gambling and that’s if they will be very sincere with their KYC terms and policies.
Most casinos avoid KYC not because they want to attract kids to their sites but to allow gamblers to gamble with privacy. KYC is often disliked by the ones who prioritize privacy and that's why some casinos allow everyone to gamble without asking for any KYC details.
KYC is in place in some casinos because of their license. It is part of their compliance to retain their license. So even if they don't want to ask the details from their players, they need to because that's part of their protocol to maintain their license.