What you saw the other day is the real world when it comes to Jetstar in ports away from the major East Coast ports.
As there is most likely no official contract in place,Jetstar get the cheap use on mainline staff and resources e.g. the true cost of using mainline staff is not taken into account.This will continue to happen and continue to place strain on the under resourced mainline staffing levels.
When Qantas staff are out tooling around on Jetstar,mainline aircraft and passengers wait for either a bay,baggage handlers or engineering support.For those who work for Jetstar,reading this may sound like sour grapes,but I can assure you that our other customer airlines get good service,but certainly not the preferential treatment and in some cases free labour and materials that Jetstar gets.