Sorry Karl, but you are incorrect.
Have a read of the NCOP (already adopted in ACT). It lists strict requirements for the "cushions"
http://www.infrastructure.gov.au/roa...Jan2011_v2.pdf
You are permitted to remove seats temporarily (i.e. to transport bulky items), however if it has been deemed that you have removed the seats permanently, your vehicle will be defected and you will require modification approval for reduced seating capacity.
A number of people who have been defected for this - especially those who have fridges or drawers where the seats normally go (even if they argue that they remove them between trips).
This applies in all states AFAIK. Even for vehicles where you can remove the seats without tools. How well it is enforced however varies between states.

