I’ve only once been asked to an event and asked to pay. It was a woman I knew through my son’s nursery and she was a bit of a clingy / needy type to be perfectly honest. That should have been enough to get alarm bells ringing. But she asked me what I was doing on the Sunday afternoon and when I hesitated, she said she was doing a casual surprise party for her husband in the x pub and it would be lovely if we could join - bring the kids, no worries, more the merrier etc. Now the pub she mentioned is one I had previously used for DH’s birthday, where there is a private room with lots of sofas etc and a lovely garden, so the kids can run around and it’s easy for people to bring young kids without babysitters etc (this was when my kids were still quite young). I did a buffet there and champagne / drinks, cake etc and brought things for the kids to do and make so the adults could relax. It was loads of people and you could stay for an hours or all afternoon. So I thought, ok sure, we could pop in for an hour.
Anyway, when we arrive as a family of six, only then is it revealed to be a sit down meal with a whole load of frankly quite odd people. It was three courses! I really didn’t want to be there hours, but they were making such a fuss of us, I felt bad feeling that way. I thought, this is very generous if them and felt a bit embarrassed. Then when we came to leave, she said it was £40 per adult and £15 per child, plus service - so it was about £160 to spend time with people I will never see again. Oh, but don’t worry about the wine, she said... That’s on us! The kids were bored out of their minds.
Anyway, that is the one and only time and I thought it was extremely bad form. Yes it was my fault for assuming it would be a casual buffet- thing, but she caught me off guard.
Every other party or event, the host pays, whether it’s at home or in some spectacular-whatever venue. I’ve never known it to be otherwise. I wouldn’t mind being told beforehand it was a pay for yourself event, it’s just very unusual.