It applies in Victoria as well.

Victoria deregulated its market before NSW/SA/Qld.

All of the eastern states (SA/QLD/NSW/VIC/Tas) are part of a single market, with interconnects and wholesale prices set every 5 minutes.

Victoria has its own "default offer" and regulator of the retail market, which is also offering similar "free power" hours.

WA could be part of the NEM with some HVDC across the Nullabor, not sure if it would be economically worthwhile though.