Unique ID
As "Single ID" AC mentioned at 00:02, there might not be a need to decrypt the passport as long as it returns a unique ID.
RFID passports (and possibly contactless credit cards) might be useful as tracking devices -- think DoubleClick or Google, but in real life.
A shop might want to observe customer shopping habits. Which sales attract the most first-time customers? How long does the average customer remain in the store (difference between entrance scan and exit scan)?
An advertiser might like to know which stores, movies, sporting events, or travel destinations a passerby frequents.
A sports venue might want to alert security if a Known Troublemaker walks through the gate.
Less savory uses are left as an exercise for the reader.
Biting the hand that feeds IT
