leaving it to the likes of NSW & Victoria to handle the majority of international travellers
To be fair, SYD and MEL were the two busiest International ports. When flying pretty much stopped, those few airlines left flying were still pretty much SYD and MEL usual carriers. BNE's problem was the business is all Pacific island, or hubbed through SIN, HKG or the middle east, and all those places locked down tight. You couldn't transit through them, so you couldn't get to BNE. China stopped. If it hadn't been for QR and Doha, BNE would have had no international business at all. For a while there, it was the only thing flying. Sure there's been the odd adhoc repat, but not many. Aviation policy in this country is SYD-centric anyway. It's probably the only airport most of the pollies could think of.
I also think NSW didn't have mandatory quarantine for domestic arrivals from interstate? This was what brought the Intl Pax cap on for arrivals into BNE, because the hotel supply was filled up with interstate detainees as a priority, with intls getting what was left.
Once domestic quarantine eased, many BNE (and other areas) hotels said they did not want quarantine pax back, as they were busier with intrastate tourism, and didn't want the hassles, issues , and restrictions that quarantine brought. They were happy to take the business when it was the only business, but they don't need or want it now.