Well I can vouch for the fact that Qantas mainline aircraft can be required to pay exhorbitant money if they need to use a Jetstar gate, having experienced it personally. In fact it was so costly that we were told to hold in the apron area until a QF designated gate became available, pax on board, engines running, even though a JQ one right next door was vacant. And QF "group" owns the terminal!
So Simon, please stop lying to us. Didn't your mum ever tell you it's naughty, or is that principal beaten out of you these days in Australian Business School?