I am sure that kida are most time gambling in real life.My friends under 18 years gamble in real life casinos,real life machines,but they more bet online but they also bet in real life.
I think when you want to gamble at the casino offline. a guard or security guard will ask your age if you look young. maybe you will need some of proving such as ID cards. because the rules that gambling should have a lifespan of over 18 years. I do not really care if you have a lifespan of 18 years and play at online gamblingapparently you have never heard about fake IDs
but yeah all of these places have age restrictions and check for ID but that is only because they will get into trouble if they don't check. and since online gambling especially with bitcoin is not regulated yet so they don't have these rules and in fact they don't care how old you are as long as you play there.