"IDing" people, one way or another, has been around for millenia...the slant of the eye, vocalization and colloquialisms, length of hair, absence (or presence) of facial hair, and so many other subtleties:
A "printed card" in and of itself makes no difference whatsoever; as if a Tutsi could hold up a piece of paper and prevent the summary execution.
edit to add: Nadsam, your testimony is heavy-weight, and I don't mean to diminish your personal experience.