Considering a mail-in ballot gets rid of ballot secrecy anyway, I don't see why they don't just allow online ballots cast with login.gov or whatever.
They mean voter buying cases, "paying you to confirm a vote for X" and see you check the card.
In ballot cabins the buyer can't come with you inside the booth to confirm, so your vote has verifiable privacy/secrecy.
It doesn't really solve all type of vote buying problems (like clientelism lists, etc), but removes that confirmation step.