Alergy
What if a crew member is allergic to specific foods?
Say the hotel has has a seafood buffet and you either can't bear to swallow a shrimp, squid, or oyster, or are allergic?
Great situation when a crew comes down with food poisioning having all been coralled into the same restaurant to eat.
Obviously, the Big Head has realised that crew are pocketing the cash and having noodle parties then sending the cash home to support their families, or worse, going out and happily spending the money shopping while being forced to layover in some place they would rather not be.