[maxerickson]

I imagine they are thinking of it being a list C document:

https://www.uscis.gov/i-9-central/acceptable-documents

(an unrestricted SSN is proof of eligibility to work in the US)

[this-dang-guy]

Yes, and no less than 3 of my former jobs required a photocopy of the card itself. You can argue legal requirements, or you can shut up and be paid.

Sometimes it's better to be paid than right. (Especially on your first few jobs)