This is a very interesting post. The replies are correct about the gravity of the situation. We’ve probably all encountered free-lancers who failed to show up for a shoot (once, because they never get a second call). OTOH, there could be circumstances beyond your control which would make it impossible for you to do the job (e.g. appendectomy).
So I would read the contract very carefully, to make sure that a serious illness (or other circumstance beyond your control, e.g. blizzard, civil unrest, car accident, flight cancellation, close family tragedy) will not also result in a financially crippling lawsuit.
Does anyone know of a contract which protects both parties in this situation?
I am not in the wedding market, but for absolutely mission-critical work, I like to be on-site, with all gear accounted for, one day ahead of schedule. For a location wedding, before I signed a contract like yours, I would definitely build that into the bid.
Good luck and please let us know how you resolve this one.
Bob C