? I voted, had car insurance and had a driver license in college registered to my school PO box.
Yes, there are some exceptions, depending on the school and the local government. For the most part though, legislative changes after 9/11 require an ID to be based on a physical residence, rather than a mailing box. Similarly, legislative changes after the 2008 financial meltdown has resulted in similar requirements for financial institutions (credit cards/bank accounts) etc.
There definitely are still some exceptions to both, but it is not the current norm.