Yes adult beverages can be tracked via the card.....however, anyone that’s been on at least one cruise ship can attest that very few crew members speak English.
And I also doubt bartenders are taking the time to check how much passengers are drinking at any given time period.
What most people don’t realize is when your on one of those boats your not in the US anymore and the crew couldn’t give 2 shits if a passenger is American.
I’ve experienced that one 1st hand.
Well I suspect that will all change now.