US Passport
Hi HB
I am not sure this is the reason about your wife passport but i would say that
when we come through customs as crew in some airports its says EU/Passports and we normally come through as a crew 10-11 people. If you wife has a American passport this would mean she would have to go to another Passport control point . And may have to wait which would hold the
crew up on departure or arrival at the airport. The airlines may think this is a problem . I am not saying this is correct but the only thing i can think off