Hi captain - when my kids were in the lower primary classes they were always given a list of the class for their Christmas cards. they don't now, but I don't know if that is because the school have stopped doing it, or if it is just because at 8 and 9 they shouldn't need to be told anymore. If it was really to stop people calling for children across the playground, you could be fairly sure that if you shouted Jack or Sophie in any school you would have loads of kids with that name - doesn't mean that they would walk out the playground with you!
It is also nothing to do with the DP act. that is complete nonsense.