The Nanny

The nanny brought a little kid to the liberry to check out books.  The child's mother didn't give the nanny her card.  I told the nanny that I'd be unable to issue the kid a card because I needed either his mom or dad to be present so that they'd be the responsible party.  She replied-- ok, but he can still check out books without a card, right?

If he would be able to check out books without a card, what would be the point of having a liberry card?