When I was 10, I regularly bought beer and cigarettes in the shop near our house. I also bought bread, eggs, milk, etc. I was buying these things for my parents. I don't think there's anything wrong with that, except for the fact that I occasionally bought sweets for myself with the change. Unsurprisingly, as a 10 year old, I was more interested in strawberry chewing gum and red licorice than beer and cigarettes (which I had tried and found to be revolting).
When I was 10, my older brother turned 16. My father started including him when he ordered wine with dinner and he had the occasional beer with his friends. I have never seen any evidence of my brother abusing alcohol.
On the other hand, I saw plenty of alcohol abuse when we moved to Ireland. The strictness of the law here leads to the same problems associated with any other illegal drug abuse. Users (in this case, minors) consume it in secret and often in uncontrolled and dangerous ways. I'd much prefer to have a 16 year old kid being kicked out of a bar for being too drunk than drinking a litre of whiskey in a field, passing out and dying of exposure.
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