If I had to guess, me thinks that there's no system to verify who's coming and who's going unless you have your registration packet and you're on a list, which may not be updated once it's created.
Most places will charge you a cancellation fee, unless you cancel 30 days (or whatever) before the event. I would think the more participants the better and keep the cancellation fees.
I would love to go, but alas, my Cobra is still sans engine and tranny.
