You're right! All of these things are true, real, and valid scenarios that can lead to this situation. Those who have relative means will often maintain a mail

You're right! All of these things are true, real, and valid scenarios that can lead to this situation. Those who have relative means will often maintain a mailbox of some sort. There are services that accept mail and scan it for you and other ways. Few of which are available to the homeless, due generally to a lack of financial means. Lacking a real permanent address doesn't inherently make you uncontactable by governments. It's the combination of lacking a permanent address and lacking the means to work around it that creates a perfect storm.