Australia has traditionally had government led national infrastructure to achieve span and system uniformity, followed on by waves of privatisation to varying degrees - for roads, power, telecommunications, etc.

It's a large (mainland USA in area equivilant) area with sparse dense pockets of population.

W.Australia has a fully independent power grid, I suspect the Northern Territory is the same. The East Coast (where the vast majority of population resides) has inter connected State grids .. including (recently) Tasmania, an island state with a great deal of hydro electricity and gas reserves.

https://en.wikipedia.org/wiki/Basslink

There's a federal road network, lesser roads are state roads, smaller roads are managed by local councils.

On Tas/Basslink:

There's quite a bit of Wind generation, too - and a whole lot of capacity for more, if the windfarms can get approval. (Roadblocks from local communities)

There's a project to duplicate basslink (500MW HVCD) - it was initially planned as 2x 750MW cables, but the three governments involved wouldn't fully agree on the increased price. Which IMO is insane because it'll be needed.

There's a dashboard showing how the various states interlink and export power between themselves[1].

[1] https://aemo.com.au/en/energy-systems/electricity/national-e...