If, however, JQ says they do not want to have the tower on duty because (in the Australian system) they have to pay for it,
Does the airline get a say in whether the TWR is open or not? I would have thought that those Terminal Nav costs (for a A320 at YBSU approx $1k = approx $5 a seat) would be passed on to the passenger. Be very interesting to see if a standard ticket is more expensive during the hours of operation of the TWR vs outside the hours. If it is the same, either JQ is absorbing the cost in the first instance (unlikely), or pocketing the difference in the second instance (more likely). The Firies are open early and the pax pay for that, and JQ would collect and pass it on via their nav fees.