I can kind of see how this could happen. We are a one car family so my kids get picked up by either SO, my mom, my dad, my step-mom, or me. And there have been times where I've had to send friends to get them. My son also goes home with his friends occasionally for play dates. The yard duties try hard to keep it all straight and have questioned when a new person comes for them. I've never sent someone my children weren't completely comfortable with though. And as a mother, if that situation HAD to occur I would have called the school ahead of time to let them know.
High Priestess JessMess, follower of the Goddess of the Coiling Way and Confiscator of Concoctions in the Order of the Curly Crusaders