I was wondering if taxes were a reason. Oddly enough, I saw this sign which is about anti-laundering and not taxes; seems that X doesn't track casino $$$ for customs purposes. Yet this sign is technically incorrect as you're supposed to file when you're carrying $10K+ off the ship, so if you did 3 $5K room charges for a total of $15K, gambled all cruise long, lost $4500 total and walked off the ship with $10,500 you're still supposed to file a customs form despite losing