What's new about that rip off?
The Federal Airports Corporation pioneered and perfected the rip of of charging for hangared aircraft years ago. And they weren't backwards in their hangar lease rates!
And as the charge would be the result of a private treaty ("You land here, you accept our terms and conditions in the fine print"), I doubt the ACCC would have any jurisdiction.
If you land/park at any private airports, take this advice: Touch toes, pinneaple inbound!