It was also arguably “unconstitutional” [1] for Australian states to close their borders with one another over the pandemic. Business magnate Clive Palmer sued Western Australia over its border closures, in fact, and even received backing from the Australian federal government [2].
Particularly in light of the patchwork framework surrounding state-mandated church closures in the US, the difference between Australia and the United States as it pertains to interstate border closures seems to be more a matter of cultural expectation, than legal impossibility. But IANAL.
US airports are highly controllable ports of entry. I think a lot more could’ve been done there had the population willed hard border closures into existence.
[1]: https://auspublaw.org/2020/08/border-closures-and-s-92-clive...
[2]: https://www.theguardian.com/australia-news/2020/aug/02/feder...
As time passes so does the understanding of civics in the US. People think the President is like a king and just decree things willy nilly not appreciating the federal and state jurisdictions and that there aren’t departments which run things without direct intervention. Cheers!
More than half of the eligible voters in each state voted (either directly or indirectly through preference based instant runoff voting) for their government. This is significantly higher political participation than almost any other country in the world, and I’m sure it contributed to the outcome.
If you want to see "porous borders" you only need to look at Africa, Asia or Europe, all of which can be walked in-between. Walking from the ME to America? Not gonna happen.
Crossing the Mediterranean is very doable with limited resources while crossing the Atlantic/Pacific with the same resources would be impossible.