Fieldmouse, you are conveniently forgetting to mention the massive debt that the Howard government inherited from Hawke/Keating. The excessive price that the airports were sold for paid off a significant amount of that debt and assisted in Australia subsequently becoming "debt free" - until Kevin 07 got his hands on the keys to the vault.
Personally, I wish the airports hadn't been sold as they were administered better (with a lower cost to the travelling public) by the FAC.