Why would a teacher insist on a hand-written note from a parent, as opposed to an email?

My kindergarten aged child’s teacher insists on a hand-written note, instead of email, for days when the child has to be dismissed to a different after school activity. I had sent emails several times, and always cc’d someone in the office, just in case the teacher was not present on the day I sent the email, to ensure that someone would get it.

I can’t understand what the advantage of a hand-written note would be: it could get lost en route in the child’s backpack, it does not have a time and date stamp on it, there’s only one copy of it. It makes no sense, and yet I, as well as the other parents, don’t want to challenge the teacher on her rule.

Is the teacher just old fashioned or could there be an actual logical reason for this demand?