My understanding is that that warning applied to the card itself, not to the number. That is, the bearer of that card has no provable relationship to the socia

My understanding is that that warning applied to the card itself, not to the number. That is, the bearer of that card has no provable relationship to the social security number on the card as it contains no attestable information (like a photograph or general description) so the card cannot be used for identification. The number itself is of course used for identification from the beginning as a unique identifier for your "account" in the social security administration.