Here is some information on how the disabled parking scheme is SUPPOSED to work here.
The Australian Disability Parking Permit has enhanced security features to help reduce the abuse of permits and it is recognised across Australia.
Permit holders can park in parking spaces showing the international symbol of access and can receive concessions in most public parking spaces where the sign or meter shows specific time limits. For further information about permits that are not part of the Australian Disability Parking Scheme, please contact the issuing agency in your area.
The national minimum standards for disability parking concessions give States and Territories the flexibility to provide additional concessions to meet the needs of local permit holders. All disability parking permit holders will therefore need to check the local rules for parking and obey all other road and parking conditions.
But unfortunately not many people take much notice of it. Here is the link if your interested.