The gas supply shortages in the eastern states of Australia arose precisely because of a lack of local supply mandate and price capping baked into the original licenses.
Western Australia has such things and had no shortages.
The inevitable result (in the West) was a transnational being limited in its ability to price gouge in a global supply crisis.
For example, were they granted a legal monopoly?
Err, by "they" do you mean Apache, BHP, BP, Chevron, KufPec, Mitsubishi Motors, Mitsui & Co, Quadrant Energy, Santos, Shell and Woodside Energy ?
(ie Australian LNG producers)
and by "legal monopoloy" do you mean "A market structure characterized by a single seller" ?
The Australian government is bringing in a price cap of $12 per gigajoule (well above historical gas prices, and well above long-term contract prices for Australian LNG in Japan) for domestic customers.
Whatever the merits of this action, it’s a very very very long way from “nationalising the sector”. The Western Australian gas industry (on the other side of the country on a completely separate grid) has long had a regulation mandating a minimum proportion of WA’s gas must be sold to domestic customers, meaning local gas prices there are unaffected by the global shifts in prices. Heck, that bastion of capitalism, the United States of America, completely banned the export of natural gas and oil until 2015.
https://www.upstreamonline.com/lng/shells-prelude-flng-facil...