It has always been this way because things are very appropriate at that moment to do them better, a minor does not have the necessary maturity to face any challenge of games of chance, however I say that when a person is 18 years old, Sometimes it is not very mature, however it is the standard age for a person to consider themselves a responsible adult in all their senses. In a casino, obviously the risks are high and you cannot go around venturing that these things can be seen in other ways. There will always be many ways so that we cannot cause problems and one is by being mature in the game.
I know people who are 30-40 years old and think like teenagers, but their actions are worthy of being punished with prison if they violate the basic principles of normal Human behavior.