Which is why Qantas has been complaining it is not making money on its international routes, why SQ flies Business only passengers on SIN-LAX; SIN-EWR.
In real life, I heard ULH is not profitable because the aircraft needs to carry extra fuel to hold the weight needed for fuel needed for the journey.
Ummmmm, because its not. Thats why.
Qantas International hasn't turned a profit in years, and desperately needs a restructure. Its competing with global airlines ( *cough*
SQ/ EK/ EY/ CX *cough*
) with much lower cost bases in the SAME
market. That is why QF Intl is hemoraging money, because its fares are not competitively priced in the global market.
Your point about ULH is correct however, as the aircraft has to burn fuel to carry fuel which makes it more expensive to operate the route.