If you don’t know the code and the machines are also hooked to the internet, they can spit out any old numbers those who do know the code and who are at the other end of the internet connection want. From Dr. Naomi Wolf at naomiwolf.substack.com:
Algorithms 101: Why the Secret Ballot — In Made-for-Cheating Electronic Voting Systems – is a Recipe for Fraud
We think of the secret ballot as being fundamental to our rights, and indeed to our democratic system, and in many ways that belief is correct. Or it certainly would be correct, if those secret ballots were cast in a verifiable, accurately- tabulating voting system.
But the secret ballot became a sacred aspect of elections, in the days when ballots were cast in boxes, using paper. There was little risk run by those who cherished the secrecy of their choices in such a system, because the ballots could always be recounted. They were physical artefacts. They either existed or they did not.
People could steal elections in this “analog” technology of paper and locked ballot boxes, of course, by destroying or hiding votes, or by bribing voters, a la Tammany Hall, or by other forms of wrongdoing, so security and chain of custody, as well as anti-corruption scrutiny, were always needed in guaranteeing accurate election counts. But there was no reason, with analog physical processing of votes, to query the tradition of the secret ballot.
Before the digital scanning of votes, you could not hack a wooden ballot box; and you could not set an algorithm to misread a pile of paper ballots. So, at the end of the day, one way or another, you were counting physical documents.