Rent, bills and chores for a shared house, in one place.
Ask for a real yes, not a thumbs-up in the chat. Have everyone promise their share and save a card now, with the rule that nobody is charged unless the trip's goal fills by its date. A promise with a saved card is a yes you can count on; a group-chat thumbs-up is not. You find out who's really coming before you put a deposit down.
Every group trip starts with eight enthusiastic yeses and ends with four people who actually pay. The gap between those numbers is where the organizer gets hurt: they book the house for eight, four flake, and they eat the difference. The problem was never the trip, it was that "I'm in" cost nobody anything to say.
The two usual ways both fail. The honor system ("just pay me later") turns the organizer into a collections agency for a trip that already happened. Collecting a real deposit up front works, but it's a hard ask months out, so people stall, and the organizer is left holding early money and sending it back every time someone drops.
A promise threads the needle. It's an easy yes, because no money leaves today, but it's a real yes, because the card is saved and the charge comes when the goal fills. Someone who won't promise was never actually coming, and you find that out now, in the planning stage, instead of at the check-in desk. Until the goal fills, anyone can Take back their promise with nothing charged.
When the goal fills and the cards are charged, the money lands with the organizer, and everyone sees the whole thing: who promised, when it charged, what's there. It's the same idea behind commit-now-pay-later for groups.