Just out of interest, as the majority of SLF on UA aircraft would be US citizens, just as Aussies prefer what they know and to fly with an airline that gives their domestic frequent flyer program a boost, UA have the advantage of much higher yield on a larger percentage of passengers.
Take for instance, a passenger departing LAX for Oz.
That passenger has no access to Aussie fares as he is originating in the US market, and must buy at USD rates.
Generally speaking, the USD fares are around double the AUD fares, so a passenger departing the LAX for SYD could expect to pay USD1900.00 for instance, where his Aussie counterpart departing SYD for LAX would be paying AUD1900.00 over the reversed port pair.
This is oversimplified, but rings true in most cases. It is all related to strength of economies and currencies, and even though yield control makes it easier to buy a seat at the USD bottom fare as it pays more, unless loadings are desperately high one could assume that a United flight with full passenger load SYDLAX would be returning at least 50% more in dollars converted into whichever currency you wish.
In the reverse, it is generally much cheaper to buy a return fare JNBSYD than it is SYDJNB due to the weak Rand. Therefore QF would generally be turning a better dollar figure than SA on a similar flight, again due to the loyalty of locals to the home team carrier.
Then we take into account local wages for crews and ground staff, and the water is muddy again.
Just thought I would throw this in to further clarify, or confuse the matter.
best all
EWL
