I think most are looking at this backwards. This system is most likely the reCaptcha of facial recognition. The same way Google already knows you're not a robot, and they just use you to improve their image recognition algos. The facial recognition at the airport is one of the few ways to get multiple pictures of people while knowing with near 100% certainty the face matches the name. The system is building out their data set. Running facial recognition in other scenarios (e.g. security footage after a crime) off a single passport photo is hard. Running facial recognition off of a data set with many different photos is much better.
