Yes it's super cheap because there isn't carbon taxes.

In the US it is also super cheap because it is a byproduct of our fracking in The Dakotas.

It's a byproduct of a lot of oil production while also having its own reserves. My office used to look at an oil refinery that was miles away, and they were just burning the natural gas off in a huge plume, not worth trying to capture and combust for production.

The fracking is also in Arkansas and Texas and many other states. An amazing amount of gas continues to be discovered. I am not a geologist but assume that Australia could dedicate resources to explore fracking gas reserves and would come up with quite bit.

sidebar, but I just realized that Australia doesnt really have mountains to speak of. Tallest mountain is around the elevation of the typical Colorado Rockies valley towns. Australia may not have the 'cap traps' required to retain large amounts of gas in the various layers going down under ground.