Probably for the same reason that Coca-Cola, Pepsi and KFC keep their trade secrets, dumb ass.
If you had a job or a marketable skill set of any sort, you might know that. But you don't.
By the way? How do you know the coding is not the problem if nobody ever gets to see it? The coding is part of the vote counting process and needs to be observed by independent observers. But unfortunately it is not.
