Also a major saving part of the business of those few airlines flying capped pax numbers into Aus is carrying decent numbers out on the return trip, plus a belly full of freight. If they have to arrive at a deserted location to drop off those arriving pax, where do the outbound pax and freight come from? If you expect them to then continue on to their original destination empty...?
If the solution is to expect outbound pax to all fly domestically to that same isolated airfield to await their outward connection, you have another problem of dealing with those passengers as well.