You wrote: “just fold the paper before you print the fake ballots.”
But when you print it over the fold marks, it shows broken impression. Shows it has been printed after folding.
Not all printing is alike.
Offset printing is high precision, high plate charge work.
Laser copy printing is another type.
regular photo copy (poor quality) is easily visible.
Imagine:
Blank ballot paper pre-printed over the entire surface with “Q” codes in permanent inks not visible to the naked eye, and then provided to all states ONLY from the Federal Election Comission to state election offices.
States then use that paper to print the “human readable” ballot in permanent black ink.
Those ballots are then “read” by optical scanners also provided ONLY by the FEC and whose software source code and construction specs are publicly available to all citizens interested.
Those optical scanners then retain all scanned ballots in locked compartments, whose keys are also issued to state elections offices by the FEC......ONLY AFTER THE ELECTION.