Originally Posted by
anon2k2
I have heard (but it could just be urban legend) that the reason why airlines check your passport before boarding international segments is that the airline would be on the hook to fly the passenger back to the point of origin if the passenger couldn't produce a valid passport at the destination.
I remember years ago someone with a ticket to Oakland, CA got his 15-minutes of "fame" when he got on a different plane and ended up in Auckland, NZ. Always found it hard to believe it was innocent.