"The P.O. now asks for ID from all people who will get mail in the box, less than a year ago this was not the case. Any suggestions?"
The P.O. now asks for ID from all *adult* people who will get mail in the box. When I recently opened a P.O. Box (as related in #6535), I provided I.D. for my real name, and also gave the name "Hamish" for a young child, "age 3". There is, as yet, no requirement to provide identification for children under the age of 18 when opening a P.O. Box.
I have not - yet - actually used this Post Office Box to receive mail, either in my real name or in the name of "Hamish." But I don't expect to encounter any problems when I do.