The E-3 visa (meant for Australians) doesn't have any work restrictions on spouses. Why isn't the administration targeting those visas/ead if this is indeed about "Hire American and buy American" ?
The quota for E-3s is 10,000/year, it gets about 30% subscribed (with new applications, renewals aren't capped), and it's providing the free and open movement of labour that the AU-US FTA requires. but also: white Australians don't trigger racist reactions & clamping down on all Australian E-3 immigrants would not be as effect of a dogwhistle.
Or could it be something else?
Maybe Americans don't tend to see their whole IT and Dev departments being filled with Australians, who are NOT willing to work in high COL areas on $60k year, share apartments and a car among 6 adults, and work 60 hours a week since the money they're saving won't buy them squat once home in Australia.
This is not true for Indians and others from low wage nations.
Most Americans aren't stupid. They know that businesses here use these visas to push down wages and working conditions. Considering this, I think Americans have been pretty damn friendly to most foreign workers for quite some time.
But eventually, even the most friendly of societies is going to say enough is enough.