I can't think of many ways to make a meal out worse than having someone dictate what I can choose
But that's the whole thing with an afternoon tea - it's a set deal.
Recently we ttavelled 100+ miles for a family member's birthday afternoon tea in a posh hotel. We were told no outside food and there was no kids menu. My DS has ASD and couldn't eat the ham sandwiches as they had mustard. I couldn't get the dairy free option as the teas were for 2 people and no one wanted to share with me. DS found the cakes too sweet. I ate the food and made myself ill as there was no other option (we were at a manor in the middle of nowhere and had only booked for afternoon tea so couldn't get the general menu).
In the end we ate our emergency stash of crisps and fruit in the car on the way home.
We still had a nice time. Our relative had a lovely birthday and enjoyed themselves, which was the main point of the day. It was their day and their choice.
After their birthday it was DS', then mine. We had buffets at home. DS and I knew which things were dairy/gluten free and/or low sugar but we didn't advertise it. Both times the buffet was absolutely demolished. I find that if we say what is dairy/gluten free/low sugar people avoid it like it's poison.
I can't believe how the addition of one word makes such a difference...
Regular OP: What is a good snack for my DC?
Regular MN: Ooh, carrot sticks and hummus is lovely, and healthy!
Vegan OP: So I've ordered a vegan lunch...
MN: OMG how dare you, that's so controlling and sounds gross and the kids will hate it and and and...