If the person has ID, then many options work, but if they don't what can a DMV and trained clerks do that others can't in some way?
Lastly, I'm not from the US but even I've heard that the DMV is a hellish place with queues hours long. Putting more barriers in front of those who are already in a tough spot (and may need to spend that time working, queueing for shelters, etc) is a big ask.