

Plenty of valid answers already, but also: Humans vs humans is an easy source of conflict. Writers could create nuanced stories of cooperation in the face of apocalyptic adversity, but it’s probably way harder to keep that interesting for multiple seasons than bad people are going to try to kill us and take our shit.
Absolutely. Not because I think it would necessarily be better off, but because I don’t want us to contribute to the empire and the loss of our economy would devastate the US.