With an eyewitness, simply saying that you think they are mistaken, with no evidence as to how they are mistaken, is sufficient. In this case, it was easier for

With an eyewitness, simply saying that you think they are mistaken, with no evidence as to how they are mistaken, is sufficient. In this case, it was easier for the courts to believe hundreds of people were lying and committing fraud, then that there might have been a problem in the software. The only way to change the court's perspective was to provide evidence that was not even accessible to the defendants. There's no reason to think that programmers are less fallible than other people.