After talking to Mom and the Wife, I just wanted to clarify that, while the boy does get frustrated with reading at times, the experience as a whole is not frustrating. The learning curve is steep, and he is definitely making progress.
The overall point of the post was that learning to read is difficult because there are no hard-and-fast rules regarding pronunciation. Just about any arbitrary letter combination has multiple exceptions that must be memorized. Really, it’s an exercise in the student recognizing the printed version of a spoken word. After that, it becomes possible to make educated guesses regarding pronouncing a new word.
Hope that makes more sense.