They could mail a qr code would would connect address to voters. That's how many voters get a voting card/ballot now. They could issue a qr code for identity

They could mail a qr code would would connect address to voters. That's how many voters get a voting card/ballot now. They could issue a qr code for identity for a driver lic or passport. Using those two keys you could allow a person to vote. In no way does it make sense to involve a blockchain. It rarely makes sense to use a blockchain with trusted or known entities.