Which is where someone pays you to vote a certain way. It follows that they want proof, so the receipt shows proof of your vote.
I think it's also likely to cause harassment outside of polling places with gangs on sidewalks asking to see the proof that people voted for their candidate. You DID get a receipt, didn't you?
Abuse of mail in / absentee ballots are one of the few frauds that actually happen. The elderly and tight-knit religious groups are particularly vulnerable.
I think he is referring to cases in the past where politicians and political parties would pay people to vote and require they bring the slip back to prove they voted for the right guy.
I think it's also likely to cause harassment outside of polling places with gangs on sidewalks asking to see the proof that people voted for their candidate. You DID get a receipt, didn't you?