I vaugely recall reading somewhere on FlyerTalk that it is cheaper to buy an ex-Australia xONEx from American Airlines than from Qantas, because you'll be assessed lower fuel fines. I've searched threads, but haven't been able to find anything about this.

Is this true, or am I imagining it? Are the fuel fines assessed based on the policies of the airline whose flight number you've booked under, the one that operates the flight, or the one that sells the ticket?

Thank you very much!