That’s not possession. Possession is control of an item. It is mere custodianship over an item, the handling of it on behalf of another and without claim of right to use. UPS drivers don’t possess the boxes in their trucks, and neither did this kid possess the beer, unless the father gave it to him to do with as he pleased. The father did not, according to the story.
Jeez I had to run out and get smokes for the old man when I was 14. But he had a printing company to run with a 100 employees. You never even thought about it.