Okay, that crossed my mind, along with some other circumstances. I know more than one person who only has one parents name on their BC. It made me wonder if any kind of extenuating circumstances happened (fire, etc), and they lost everything, how much of a hard time would they have? Some of them have absolutely no clue who their father is. They were never told, and some could never find out.
** And of course obvious citizenship concerns, and problems elderly might have. Most the women in my area who never drove, and might have issues getting an ID, have passed away, but there are still a pretty good number. That was a large common. I did see that some states allow a copy of a bill as ID, and that's at least not so bad/cut & dry.