I think surfacing additional information would help increase confidence in the system when it raises a problem.
For example, keep a running passengerCount (or rather display it since it must(?) exist).
If someone has a copied pass, their screen can show:
Current Passenger Count 10
This Pass Last Scanned at 5
If the fraudster & legitimate passenger are back-to-back, that might add some confusion for the agent so they'd need a good way to display this. They can call out to the last person to come back to clear up confusion.
If the fraudster was much earlier, they'd have to go find them. Maybe take a picture of each passenger during pass-scan.
Or simpler: this would be simplified by using Steffen Method boarding [1]: you should know exactly which seat matches a given passenger count number.
I loved playing Psychopath back in 2006 and built a Java clone in 2007 for a class. I love how many awesome puzzles emerge as people pieced them together to make levels on top of the simple rules. I also remember enjoying Stick Avalanche & Boomshine. Thanks for all the fun times & awesome to bump into you!
6,7,8
6,7,5,3
6,7,1,4,3
6,8,4,3
6,8,7
6,3,5,7
6,2,1,5,7
8,1,5,7
8,6,7
8,4,2,1,6
8,4,3,6
8,7,6