Rescheduling is the normal case. A booking that survives to its original date is the exception, so the system has to move people gracefully rather than treat every change as an incident.
A pilot's paperwork is a flying restriction. Ratings, medical validity and recent hours determine who may take a passenger, and discovering an expired document on the hill costs a morning and possibly more.
Equipment ages on a schedule. Reserve parachutes need repacking and wings need inspection at stated intervals, and a kit register with dates is what keeps a fleet legally flyable.
Weight is an operational fact. A passenger's weight determines the wing, the pilot who can fly it and sometimes whether the flight happens at all, so it belongs in the booking rather than in a surprise at the launch.