There is no requirement for an agent to assume your nationality and let you through, no? You still need to show your passport even when returning home.
Of course, all this sovereign citizen nonsense ignores reality and tries to pursue (nonexistent) legal 'gotchas' like you're rules-lawyering your way into a 'rules as written' game breaking combo in Magic: The Gathering.
https://www.nationalgeographic.com/travel/article/a-history-...
Even in the period of supposedly free international travel before WW1, the US government barred a large number of people from entering the country.
There are plenty of videos on YouTube of people sitting in their cars and just repeating "Am I being detained?" and "Am I free to go?" over and over until the CBP officer gets tired of it and lets them go. As should be the case, IMO; the existence of these checkpoints is absurd.
I have no dog in this fight, just an intellectual curiosity.
It would also only really apply at a land crossing, I imagine. You can't even get on a plane that's entering the US without showing your passport at the departure gate. At that point your only option if you really are without documentation is to find the nearest US consulate and get some travel papers.
You don't really have to "trust YT" here; there are plenty of videos of the encounters themselves, where people stubbornly refuse to answer the CBP agent's questions until the agent gives up and waves them through. Sure, you can argue that they're staged or something, but the sheer number of them would at least put some doubt on that claim.
My last flight to Seattle from Mexico a few weeks ago (also, note that I'm an LPR, and not a citizen) I walked up to the CBP immigration counter, looked at a webcam, the officer looked at his computer, said "[my name]?" "Yes." "You're good to go."
I had, of course, my passport and green card on me, but they were held by my side the entire time. He didn't ask for them.
/before people ask: I’m white my wife is Mexican.
In any case, the 'Freedom Auditor' concept mentioned in your initial comment sounds, to me, like the express line to "Please wait over here while I get my supervisor" from your CBP agent.
Please clarify if I’ve got the wrong read on what you mean though.
Like I said, the best I’ve found is some information on a movement of “First Amendment auditors” but a literal reading of what they’re about has them testing First Amendment jurisprudence which isn’t exactly stress-testing your Fourth Amendment rights in an reentry line at the border, hence the request for clarification.