It's not rocket science but does require some foresight. Realistically it would take 6 months - 1 year to fully build out quarantine sites that could fully replace hotel quarantine.

If the governments had started on this in March 2020 it would have been worthwhile but these facilities are only just starting to be built now, are too small to entirely replace hotel quarantine, and will be largely redundant by the time they open if NSW and VIC continue on their current paths.