As long as it is one bottle then I don't see the harm but it's unlikely to be one bottle and I wouldn't allow it unsupervised in public.
At 15, I was drinking in nightclubs (pre-photo ID age, just). Behind my mums back.
We were also allowed those little stubby bottles of beer and cheap wine from about 13/14 at a friends house for parties (in the late 90s).
Al this 'ban it and you make it popular' stuff is nonsense. We were never banned from it and yet we still spent our late teens and early twenties going out getting absolutely smashed frequently. It was popular regardless.
Now I do look back a bit horrified at what went on, if I'm honest. It was irresponsible of the adults to let us do that though we thought it was cool at the time. We all smoked then too. I'm surprised none of us ever came to any harm.
I have a long while before my daughters become teens, but I intend to educate them on the dangers and allow small, reasonable consumption from late teens but supervised, by me. Hopefully the trend for teens drinking being uncool will continue and by then mine won't be bothered (I'd rather they had a wine than took drugs though, which seems to be more popular with teenagers than it was when I was young, anyway!).