As far as I know casinos can get a hefty fine if law enforcement can prove that their services were used by minors. Therefore, casino owners try not to get involved with children, as it can bring them problems. Naturally, modern children have very good computer skills, graphic programs, familiar with the Darkweb, etc. so they can easily bypass the restrictions of the casino up to KYC on someone else's documents. Is it the casino owners fault, I personally don't think so.
Maybe that may happen to casino that lets minors playing gambling. But we know that the casino can do that easily and allow minors to comes to their place secretly. Not many teenagers have a good self control to protect them from the big risks of playing gambling. Teenage exposure to gambling can easily happen especially when they don't talking to adult people about what is the risk and the effect of playing gambling. But that is not a casino wrong because playing gambling or not is a choice for all people so they need to determine by themselves. If they think playing gambling can makes them lose too much money, they don't have to playing gambling instead doing other things.