Surely not hard but why?

Easier to steal elections?

Don't have to bother with gerrymandering, or slick legal ways to arrest people for voting with the wrong documents. Or just good old fashioned intimidation, like making the polling place the police station or the ICE detention facility.

It's just a lot smoother process when you can simply write some software to manipulate the count.

Who's gonna check?

(No, seriously, Who's gonna check? Because you also need to layoff everyone in that department once you're in power.)

Corrupted OCR won't help you steal elections. The result counting is a different process, with well designed checks and safeguards.

The problem is that once the counts are done and have been reported a lot of places then print those results out on paper and then scan those papers into a PDF for anyone who asks for a copy!

Many jurisdictions do risk-limiting audits using the original ballots, so futzing with the results wouldn't necessarily make that easier. Also, cast vote records are public in many states - those are records of each ballot cast. So people can check.

I think you mean risk limiting, right?

Yes, thanks! Fixed.

Freudian Slip?

You may consider reading about risk limiting audits. https://www.voting.works/audits

Sounds like an IOCCC challenge (but a much bigger haystack in which to hide the hack).