By international standards, Australia is quite bureaucratic and over-governed.
So yes, each the transport department of each state or territory government has established itself (since around 1920) as the monopoly provider of number plates. And, to leech more money from suckers, most have set up a personalised plate operation, for example:
Personalised Plates Queensland.
The states and territories act to protect their monopoly, using their coercive powers (ie their pet authority figures and the so-called justice system). Just last year, all the state and territory were frightened when an organisation started promoting 'perpetual vehicle registration' for motor vehicles before it had gained full official permission. See the Queensland Transport Department's rant against Perpetual Vehicle Registration (and their threat to use their agents of coercion against you) in the middle of their page on
Licencing & Registration.
I might sound angry. I am, because QLD governments have not invested adequately in highways or other roads. But the authorities continue to blame accidents on driving with excessive speed - when the poor state of the roads shoulders the blame (sure, people drive at excessive speed, if you mean excessive for the poor condition of the roads. But the posted and mandated maximum speed is in excess of what would be safe on those lousy roads!).
Fear not, it gets worse every year. And will continue to do so.