This seems like trying to find a problem for the email solution. The mail system as it is is working. It has been for many years. It costs a non-significant am

This seems like trying to find a problem for the email solution. The mail system as it is is working. It has been for many years. It costs a non-significant amount of money to send mail, so this takes care of the spam problem: spam exists but isn't free so it isn't profitable. There's no need to have PKI or "personal certificates" infrastructure so even 80-year olds can receive and read mail. I have a mailbox. The government is obligated to send stuff there. If I move, I can redirect my mail. I would hate to have a (new) obligation to check my "government-assigned" email box (protected by "PKI" or "personal certificate"), or face penalties for not doing that — in addition to my obligation to check my mailbox. My parents would never be able to take care of it, so it would fall (again) on me to check their email boxes as well.