The problem is authorities can't detain kids that are involved in gambling. Instead of catching kids, the authority should capture the operator first because the operator is the root of the problem. These entrapment is a good idea but the way you wanted it to proceeds is impossible to happen.
Am not saying to detain the kid gambler but to give him corporal punishment and let him go. Op will understand this better than you because he is from the same country as me and he knows what am talking about. We know how this things are done. Just one encounter with the soldier arrangement and you never get that kid returning back to the gambling shop.