Yeah, you have to keep falling back - my idea was that assuming homeless don't move very rapidly from one location to another, you'd have people at the DMV or shelter or wherever you put this who actually recognize the person and can "vouch" for them.

It's not an easy problem to solve with "one quick trick" by any means. Part of the reason the DMV can be hellish (in the US at least) is they have to deal with everyone who has an ID, not just the "good customers".