The wiki page explains it pretty well.

You mean like where it specifically says its most common purpose is unionist and that the racist usage is unwelcome among its primary users?

Whilst some Australians view it as a symbol of nationality, it has more often been employed by historical societies, re-enactors and trade unions such as the former Builders Labourers Federation. More recently, far-right organisations and political parties have adopted it, including the Australia First Party, National Action, and some neo-Nazi groups, much to the frustration of more established socialist and progressive claimants.