I find it really weird when people put the two options as drinking at home or going out to drink with strangers. It seems an odd need to justify a choice they're either uncomfortable with or fear being judged for. I don't think you'd be U either way.
I don't have a concern of my children going to go drink with strangers (my oldest has been bigger than me for years, it's not like I could stop him if he wanted to do so). We've just had discussions over the years about harm reduction with drugs, about considering the possible benefits with the risks, and that if they want to try alcohol, we'd prefer to take them through the steps at home and see how they react to it first. We discuss that there is varying quality research on the topic, but for now the understanding is the risk of addiction has hereditary components and that early exposure and community encouragement also increases the risk and as they have addicts on pretty much every side of their family, they may need to be more cautious and considered on this than some other people they know.
My oldest is 16 and had his first taste a few months back (and I've no reason to think he's lying). He asked and as agreed in our previous discussions on alcohol and harm reduction, his father showed him how to mix a drink (lime vodka and cola) and they each had a cup with about a unit in it while we all watched a movie together and ate. He didn't finish half of it and hasn't asked for any since.
For me, I have no idea when I had my first taste. I know my brother had a drink spiked when he was about 7 (and I do mean spiked as in given a drink he thought was juice, but was actually spiked with wine cooler for the adult's amusement. He ended up with a sick stomach and really out of it, which she thought was hilarious). I first noticed a spiked drink when I was a bit older than that, I wouldn't drink anything that had that smell (or that someone was very eager for me to drink), but I might have missed something.
I started to drink at 30 and can count on my fingers how often I've chosen to drink alcohol. My spouse started to drink at about 15 and I've never seen him drunk, he drinks maybe once a year at work events if that, but he also had little encouragement to drink growing up compared to me (it was more a we're bored thing than communally encouraged) and he put in early a process to keep himself from drinking too much. There are too many factors to put an age on it.
Don't know why people try and stop their teens from drinking. They're going to do it anyway!
Plenty of teenagers don't drink alcohol. Maybe because I was one of them and had to deal the messy consequences of that attitude with others, so I do restrict access in my home and wouldn't supply for outside of my home. I don't want other teenagers to put in the position I was in, caring for others who had been supplied drink by parents who made excuses that it was better they drank at a friends house (that they didn't check an adult would be there for) than out and about (because of course they're going to drink so why consider not drinking an option).
I find it very lazy parenting to just go 'well, they're going to do it anyway' and not at least ensure access is restricted until basic harm reduction information is instilled. Having dealt with those whose pretty much only information on safety is drinking at a friends' house and not driving, it does not go well when someone gets really sick or starts to suffer other negative side effects. Alcohol is a recreational drug, there are potentially enjoyable benefits, but there are also risks just like with others.
I don't think I can entirely stop it, as I said my oldest is far too big for me to think I can stop him from much that he wants, but that doesn't mean I shouldn't do anything to restrict access or try to discourage riskier behaviour. It's about harm reduction, not elimination which is impossible, and part of that can be restriction and sometimes it's the tools and information to figure things out - like being clear that some people enjoy drinking and some people don't, rather than continue this myth that it's something everyone does and enjoys. Teenagers have enough pressure these days of things 'everyone does' that are a lot of rubbish, this one needs binned.