The size of the company should have no bearing on its workers...

The size of the company should have no bearing on its workers ability to move in and out of their site . The authorities have made ample information available to allow for free movement under exemption of specialists for essential works. It would be quite unfair if BHP were able to exempt their workers while other smaller miners or prospectors were not able to do the same. Any companies resources to adapt to these moving rules, and coy risk appetite will possibly be a bigger factor.

Then again, the govt may turn around any day and deem iron ore and gold essential (for ongoing govt revenue) and other commodities (potash?) non-essential. Or they could outline further site specific restrictions depending on indigenous risk factors that may close off operations at certain projects.