> Baggage allowance is clearly stated when ordering tickets online from a serious airline Sure, though, those fields (marketing carrier/flight + operating carr

> Baggage allowance is clearly stated when ordering tickets online from a serious airline Sure, though, those fields (marketing carrier/flight + operating carrier/flight) drive things like what the kiosk or agent charges you. Say you booked on AA, but part of your travel was a codeshare on BA. That integration is how all those terms and conditions get followed. Why you pay the AA $50 overweight charge for your big bag rather than the BA $65 charge. Similar for refunds and loyalty programs. Take loyalty...the points aren't awarded until you fly, via a "lift" message. And if it doesn't have the right marketing carrier + flight number, that "lift" message doesn't get processed. Yes, it's old and rooted in the 60's. And yes, it's got issues. Nobody is selling it as elegant. Just that it serves useful functions now, and that it's ensnared in enough separate internal and external systems that replacing it with something better is not trivial.