I could still sell my vote to my boss in the typical system.
And we could use cryptography to vote anonymously after authentication online.
And we could use cryptography to vote anonymously after authentication online.
You go into the voting booth alone.
If someone is willing to sell their vote in the first place, they have zero incentive to vote for another candidate. They only have to trust the buyer to follow up on his promise (which is required in any other scenario also).