Well here in my country minors are not allowed gambling with school uniforms and of course the age limit and even in computer shops they aren't allowed as well unless it's weekend or they are just doing projects not video games. This situation mostly happen in third world countries like mine.
Minors are not allowed playing gambling but they can still playing gambling secretly with their friends. I have seen that happens to many younger and that makes the prohibition is looks no use. It needs supervision from parents to always supervise their children from gambling and explain that playing gambling can cause them lose their money and the worst, they can becomes addicted to gambling. Without supervision from their parents, children can still playing gambling with their friends and that can gives them many problems but they will not realizes that because they only see the fun from playing gambling. Many children will becomes addicted to gambling if parents not takes it seriously and that can ruins their children future. Their teachers also needs to explain about the risks of playing gambling to students.