The reason humans can pattern match text is that we've seen so much of it. Get a highly-ornate English script font and most people have a hard time of it. And when you do figure it out, a lot of it is looking at two characters and saying, "Well, this one looks more like an 'I' than that one does, so the other one must be the 'L'."
A deterministic program works from the assumtion that we're automating a well-understood process. I don't think alphabet recognition is well understood quantitatively. Which pretty much means you don't write the program, you train it.