A good question
@DCPU. Australia does piggy back off some overseas standards, but our Australian design rule (ADR) compliance approval process has a lot of unique requirements.
However Ineos increased the GVM by 50kg to 3550kg for Australia, which has resulted in the the Grenadier now being classified as medium goods vehicle (NB) here, rather than a light goods (NA) or off road passenger vehicle (MC). As. result it only has to meet a less stringent set of ADRs and is no longer is subject to our luxury car tax, saving the buyer around $10k.
Toyota also did the same thing soon after Ineos with the 70 series Land Cruiser, but only upped the gvm by 10kg to 3510kg.
Link to the current ADR definitions and vehicle categories
https://www.legislation.gov.au/Details/F2022C01069
Cheers
Steve