This is a minor distinction to make it clear in writing, same as De vs de in Norwegian, and several other languages. It's a common way of turning a plural into

This is a minor distinction to make it clear in writing, same as De vs de in Norwegian, and several other languages. It's a common way of turning a plural into a formal address. Incidentally, in Norwegian the formal form is now so archaic that short of communicating very formally with a very old person, in most cases it will come across as rude and sarcastic (you're implying someone is seriously up themselves)