Even with automation, this nefarious vote-manipulation practice may take place.
How to foil it is the question.
A possible answer is this: Poll inspectors should make sure that voters may not bring in anything that looks like a ballot that is NOT folded at least 4 times. Sample ballots are ok so the voter knows his wants, but they should not look like real ballots, and folding them makes sure no one from the outside has given him a renegade pre-shaded real ballot.
For more assurance, poll inspectors should also make sure that voters leave the precinct with only folded sample ballots. That way, if they intend to “give away” a real ballot, it will have to be folded and (it is hoped) will not be useful for the lanzadera chain.
There you are. If you are an honest candidate, brief your poll watchers. If they are allowed cameras, let them take pictures of lanzadera suspects. Have them send the pics to the citizen volunteer arms. Tell them to complain to the poll inspectors. The school teachers will be the honest heroes of this election.