As a non-American, the whole topic has long been a mystery to me.
My school had a Head Girl (most schools had Head Boy as well, but as a girls’ school, obviously we didn’t), who was picked by the staff, whose job was basically to represent the school when they wanted a student representative to collect an award or something. I think I remember who it was, but there wasn’t much fuss about it. One assembly when it was announced, and that’s about it.
Also a selection of prefects who were supposed to help run stuff for younger students like lunch clubs, also each class of first (and second, I think?) years were assigned two prefects with the intent of giving the incoming students someone older but not adult to talk to about school or life stuff. I seem to remember there being some opportunity to volunteer as one, I didn’t, so I don’t know quite how it worked, but I know it was staff choice, not chosen by other students.
No councils, committees, ‘Queens’ (or Kings, again) or any kind of elections.
There was a school “Leaver’s Ball” which I didn’t go to 'cos my boyfriend wouldn’t be allowed to attend, only boys from our partner school could be invited. One end of year ‘speech day’ where awards were presented, plus a ceremony awarding GCSE (normal age 15-16) and A level (17-18) results (the two national exams at the time), but it was in school holidays and pretty boring. I think I went to my GCSE one, I didn’t for the A level one.
Sports teams were barely relevant, we’d get the odd mention that our ‘X’ team had won a match or tournament, but I couldn’t tell you who was on what team, unless they’d mentioned it themselves. The only one anyone cared about was the annual hockey match with the boys’ school, which we usually won because they didn’t want to tackle girls. Any other club was in school only, no competitions with other schools.
There was a year book, but it was just photos and a rather dreary summary of the year by some of the teachers, no student quotes, and it was just done by the local printers, no student involvement. I never got one, they were expensive, not popular and were viewed as a naff money making attempt by most students.
It always seemed so weird the way that films showed so much extracurricular stuff in US schools, and it all seemed so terribly important to everyone, when we just came in, went to classes and went home. I always assumed it was a huge exaggeration before I joined this board.