Do we really need state governments

or should we just give up on them and have one central one?
I mean, Australia has to be one of the most over-governed countries in the world.
Think of it we have "local government" - councils or shires, according to the state you live in, have their say in  our lives. Then we have state governments. They run, apart from Queensland, like mini versions of Westminster. (Queensland only has one house.) Then there is the federal government in Canberra.
They all have slightly different responsibilities but they also all overlap at some points. 
The laws, rules, regulations etc. are different for each state and for the Commonwealth. It's a lawyer's banquet - and mostly unnecessary.  
Commonwealth law over rides state law where the two differ.  If that is the case why don't we just move all powers to Canberra?
Every year there are arguments between Canberra and the states and also between the states over who is going to get what funding and what they are going to get funding for. Everyone thinks they are hard done by, that some states get more than their fair share and more. 
The state I live in is not performing well. It has lost some major business in the last few years - notably in the car industry. It was always going to happen but successive governments didn't want to recognise it. Local interests kept propping it up. Nothing was done about possible alternatives. Now we are paying the price. If we had been governed from one central point then things may not have been quite so bad. We might not have wasted so much money trying to resuscitate that which could not be resuscitated. 
But if we moved more power to Canberra and had national policies on education, health, housing, and more we could possibly do more.  
Let's face it. Downunder has about 25 million people. Yes they are spread out but modern communications mean instant communications. It could be done.
I just don't see those Premiers in their opulent offices being happy about it.