Gladys needs to do what other states have done. Those states who have banned NSW citizens from entering, like Tasmania, WA or Qld. Close the door to International arrivals.
Let other states carry a a disproportionate share of the load for a change instead of letting NSW manage the lions share of returning travellers. If they don't want NSW citizens in their states, why should NSW let their citizens into NSW-managed quarantine with the attendant risks that entails?
At least Tasmania and Queensland are, for now, being sensible about it and limiting it to the LGA as opposed to the entire state like a certain asreclown in the west...