Tower always owns the runways. The difference at Bankstown is that Tower also owns the taxiways between the runways.
One thing that's not clear with the new rules is who owns an inactive runway at Bankstown. In practice it's just a taxiway, but the new rules have elevated it to an undefined sub-class that is more than a taxiway (since you need a clearance to use it) but less than a runway (because it's inactive, and is outside the runway in use)