I think there is a simple way to counter-act vote buying/coercion: if the voter has a mechanism to cheat the cheater. If I can accept a hundred bucks to vote A,

I think there is a simple way to counter-act vote buying/coercion: if the voter has a mechanism to cheat the cheater. If I can accept a hundred bucks to vote A, then walk around the corner and change my vote to B in secret, it creates sufficient disincentive to buy or coerce votes.