You have a list of citizens, their personal information are stored in your country databases. They have a unique key pair assigned at some point during their life (let's call it Citizen Key, may be paired to a Citizen ID or something like this).

There is a new voting event, each citizen can now create a voting wallet using their Citizen Key then vote on the various motions by sending a transaction to a destination wallet created for this event.

At the end of the voting event, the votes are counted and no transaction can be send to the destination wallet.

You do have a central authority, it's the country (or state). Only citizens can vote, and only citizens have a valid set of keys.

The benefits is that anyone voting or people who want to verify the voting numbers can do, and without having to trust the software managing the database (I mean, you of course have to trust the blockchain itself...).