It's the jump from word-as-sound to word-as-symbol, which I think a lot of people never make, partially because it's not particularly useful in their lives.
I suspect those involved in programming skew very much towards the word-as-symbol, but whether that is causative or correlative I can't say.
I definitely belong to the word-as-symbol camp when reading in my native Norwegian. Besides, I am a programmer (A shoddy one in all but assembly language, though...)
Interestingly, perhaps, is that I recently made the transition from word-as-sound to word-as-symbol in another language - morse code; that felt very odd while it was going on - I have parsed words character by character for a couple of decades, and suddenly, I found my decoding lagging further behind - I had started hearing words as units, rather than composites of characters. Funnily enough, it was through no conscious effort - just happened, over the course of a few hours.
Full literacy in alphabetic-phonetic languages includes the steps of (1) no longer sounding out words aloud and (2) no longer sounding out most words in your head, but rather grasping the shape of the word immediately.