Originally Posted by rufus102
..I'm not sure how many UA fliers are OZ-US-OZ rather than the vice versa, but that's a possible reason....
That might be worth knowing. In either case it's many, many. Whenever (well, not always but often) the UA desk in Sydney denies you a reasonable request they like to mention that Australia has the highest 1K density per capita. No idea if that can be true but it sounds so intuitive, given that you have to fly at least 7400 miles to get to the US...
Still I think it's a charming and smart excuse.