I still don't get why another parent wouldn't ask how the other parents feel
I have the feeling that this is a discussion by people with younger children who don't have a great deal of experience with teenagers. For a start off, how would I ask the parents of teenagers who come to the house? I don't know them, I've never met them, I don't have phone numbers or addresses. Are you suggesting I should quiz visitors to the house to get their parents' contact details? Do you think, perhaps, that having sixteen year old children is a world of parents contacting each other about playdates?
My younger, 16, went to a family New Year party at the house of one of her friends. I vaguely know the hosts to the point that I might recognise he father in the street, but I don't think I've ever met the mother. She drank there, served by the hosts, I gather. She got an Uber there, texted me to wish me a happy new year and arrived back the following day, given a lift by the hosts who were passing our way. There were about a dozen kids at the party. Are you proposing that the hosts should have quizzed guests as they arrived, phoned parents for their views on (entirely legal) alcohol, and then used a marked up photo inventory of guests to determine who was allowed access to the wine on the table?
I would offer alcohol to other guests in the house if I were offering it to my own children, just as I would offer pork if we were having hotdogs. It is no more my responsibility to enforce other people's views on alcohol than it is my responsibility to enforce other people's views on vegetarianism, kosher or halal. If you think you're going to get a point-by-point agreement on food and drink with the parents in houses your sixteen year old children visit, you're going to be sorely disappointed.
My dd went to a friend's house and her mum asked if it would be ok for them to walk into town.
Yes, that's exactly how it works with sixteen year olds
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