If underage kid is gambling it is a problem for his parents, they should take care of him and tell him that gambling can lead him to bad end. If kid is using his own money to gamble then let him do it.
He will lose it sooner or later and stop.
Parental guidance is not the job of the government it is each family to be responsible and discipline their children. They can simply put some blocking software to block online gambling sites. But if their kid is too techie enough then sorry for them, its their negligence if their kid is going to get addicted with online gambling.