A waiver names its ticket, and the door can see it
Telling whether the person holding a specific ticket had signed used to mean eyeballing a name against a list, which falls apart the moment two attendees share a name. Each ticket now carries its own signed acceptance, and scanning it at check-in shows exactly what's known: signed, accepted, part of a group waiver, or not yet in. A missing waiver never blocks a paying rider at the gate, it just tells the person checking them in.