These are particularly high value assets. They must deploy each aircraft on whichever route will yield the highest profit for the company. If Newcastle is not that route and XYZ is, the airline is correct to prioritise the service to XYZ. Shareholders expect no less. Optimisation of ROI is paramount.
You should instead applaud the airline for committing two flights per day to the NCL-BRS route, however sub-optimal you consider the schedule to be. They could undoubtedly command much higher yields by running just the one.
Bit of a flaw in the logic, Shed?