Cool option if you have found some candidates in Singapore or Chile but they’re two small-ish countries (relatively speaking - ~25 million combined, compared to the >7 billion in the rest of the world), that probably won’t move the needle much.
US Immigration is ridiculous in how arbitrary it is. Where you are born matters more than who you are.
A simple process isn’t enough when most companies are terrified of dealing with immigration topics due to unknown (often non-existent) issues.
Or you could layer on another lie if you were feeling frisky - "I don't remember being asked that specific question, we briefly talked about it but I thought they understood the implication of the TN visa. Anyway, here's the process, it's super simple..."
If they're an organization with a competent HR department they should be able to manage - they'll be happy enough that they found a good candidate. As long as it's as simple as the person claims (sign letter, problem solved) it'll only be as much of a "problem" as finding out someone you offered an non-remote job to wanted to work 2 days out of each week from home because they have a kid.
Explain how these exceptions are not "some sort of classist system" that favours some nations over many others?
Define how this was the "will of a democratic people"? Who got asked for these special country exceptions? Do the American people even know about this?
American immigration is utterly broken. I stand by that.