But surely a bum on the seat is a bum on the seat, does it really matter who's.
Well, if they are on a no-fly list, it is a matter of security! Perhaps your mate isn't entitled to purchase a ticket in their own name because on the last flight they were on they got really drunk and tried to open a door (
read one example here). Perhaps they've attacked another passenger or physically assaulted a cabin crew or security staff (
another example here). Perhaps they've otherwise jeopardised or made a threat against the safety of the plane. Perhaps they're under investigation for a crime and have had their passport confiscated. And if they start getting violent or causing a problem during the flight, guess who's going to have to deal with it?
I work in Europe, so I can't confirm the situation for AA or CX, but if it's an EU-OPS regulated flight, it is a requirement that anyone who enters a plane is authorised to, and therefore it is a requirement that the name on the boarding pass matches the photo ID of the person, and the photo ID of the person matches the person's face. Airlines may differ on how they implement this. On my airline, my colleague at the gate will check the photo ID, and then the cabin crew at the door checks you've been through the normal passenger route in possession of a valid boarding pass (i.e. haven't jumped over the airport fence to get onto the apron or you're not an airside garbage man who's just been made redundant with a score to settle.) It also helps to ensure the pax manifest is accurate. As already said, it helps identify pax who are by accident trying to board the wrong plane (a regular occurrence), and then finally, it lets us separate those who need to turn left from those who need to turn right...
If you only want to go from a to b, one-way tickets are available on most airlines (provided you can meet immigration rules - for example, many countries require tourists have an outbound ticket).
Otherwise, you're always welcome to take the train (although I'm sure they'll still ask to see your ticket).
