One organizer collects from every household or classmate into one visible place, and the venue, catering, and supplies come out of that table. With a big scattered group, a public record beats tracking dozens of separate payments.
A reunion is the widest group you'll ever collect from: cousins across the country, classmates you haven't seen in a decade, dozens of people paying in dribs and drabs. One person volunteers to organize, fronts the pavilion deposit and the catering, and then spends months collecting from people through five different apps.
A reunion has a long tail of expenses: the printed shirts, the rented tables, the photographer, the extra ice run on the day. Instead of the organizer fronting each one and requesting people back, collect a little extra into the table so those come out of shared money.
Whoever pays for a reunion cost requests that amount from the table, the organizer approves it, and the group sees it come out. Nobody keeps a side ledger for a hundred-person event, and the leftover is on the record to save for next time or send back. (A smaller family get-together with a milestone? See collecting for a group birthday.)
The organizer holds the money the way one person always ends up doing, only now everyone sees every dollar. It goes through Stripe to the organizer; TableCash never holds it and is just the record.