Drunkenness is different. I don’t equate drinking with drunk.
Kids around here drink one drink with the adults if they are over 12 or so, like they do in Germany and Italy, and as is legal, it is legal to do so in the privacy of one’s home.
They learn that drinking is not a mystery, they don’t see drunken adults, and they find drunken peers stupid, horrible and undesirable.
Anecdotal.
There are far more teenagers who are drinking irresponsibly - as well as unlawfully, I might add - than there are as you described. Furthermore, you must be joking. Germany? Sorry, but my family lives in Germany. A few years ago our nephew was busted stone drunk with his buddies by their dad. He will still attending Gymnasium. His father expressed great concern over his drinking, and now as a grown young man, the son really has a problem. This is a norm in Germany.
My family has traveled throughout Europe. Young Germans love to brag about their early-age drinking, and they have the Facebook videos, drunken stupor, and “What happened last-night?” stories to prove it.
I know that in Italian culture, children are given diluted wine at an early age. The two cultures cannot be compared in their view and approach to under-aged drinking.