I think the photo ID should be the base. There may have to be some exceptions--you gave an example--but I think we should start from the base, the principle. Everybody should know that's the operating principle.
Perhaps in the case of people who don't have them, as I say, an oath could be sworn at a registration table with representatives of all the parties there. Perhaps we could do what you do in the old world polls: you get someone whose ID has already been verified, who has already voted in the same polling station, to vouch for the person. That may be another way to deal with seniors and people like that.
There would probably have to be some exceptions, but I think the base operating principle should be that photo ID is required.