Yes, I hear you, and I understand what you mean, and I think it's inappropriate.
Let me go on. One of the things to which the homeless are often subject is losing their possessions, etc. Even if you had some sort of a way to provide proper identification, chances are it might not survive very long. It means that you can't get there from here, using a straight ID system.
Do you have any thoughts on what alternatives might be available, other than the only one really on the table, so that they would somehow get the necessary identification and have it at the time when an election might occur? Are there any other options?