G'day Josh
You're displaying your ignorance here son.
Australia is a Federation of states - the various colonies agreed to make an overarching government structure and give it certain powers.
Section 51 of the Constitution describes those powers.
The High Court has ruled again and again and again that certain things cannot be taxed or administered by the Federal Government, because it is not given that power under Section 51 of the constitution.
The Constitution is not a long document - I recommend you (and all young intelligent Australians) read it
