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Yes, if there are casinos that do not apply any restrictions or do not apply the rule that a minor is not allowed to participate in gambling activities in their betting shop then yes,
the government should step in to solve this problem, and if indeed from the beginning the government only allowed gambling for people who are adults then yes, I think there is no reason for any defense for the government not to immediately solve this problem.
That's what we need government for: to regulate things like gambling so that underage kids weren't engaged with it. Although I don't know such people personally, I heard that there are people who would do anything for money, including allowing kids to gamble only to gain more profits. No one before 20 should gamble, period. It's my personal opinion, I know that it's allowed to gamble from 18 years of age in most places, unfortunately.