Statement: A voice interface can also be important as it is the voice that will be required for them to cast their vote.
How does a voice interface meet privacy requirements? Will voting booths need to be soundproof?
While you are pondering that, consider Florida. Remember the “hanging chad” or unproperly punched paper ballots in Florida several elections ago? According to: https://www.accessthevote.org/voting-in-florida/where-do-i-vote/florida-voting-machines/ ,
Florida uses voting machines from at least six different vendors and they consist of everything from DRE (direct recorded entry) using touchscreen, to optical scanners that read marked paper ballots. The question on voting is designed to provoke thought.
If the HCI designer tries to meet the objectives of universality in voting then should that really require another person as an assistant vote caster?