Hi Bomb Thrower,
This sounds like a very interesting situation. In most buildings the power boards will be secured by (in an old building) what is known as an NMB key or (in a new building) an abloy key. These are standard keys that a qualified licensed electrician or the energy provider will have a copy of.
This allows for an owner or resident to call Ausgrid to attend after hours and reactivate the power to the unit.
You may find that there could be a requirement in the BCA or Ausgrid standards to have the separate external main switch where the meter is located.
Mr S