The first time you type your newly created password, it's like executing a program/script that goes: "Type('a'); Type('b'); ..."
Once it becomes muscle memory, there's no longer a script (which is why the password is no longer consciously available) for you to execute: you trigger the first finger motion, then it all happens more or less automatically, since the individual finger motions are linked together by sensory cues. Software becomes firmware as it were. I suspect those who claim not to subvocalize could be in an analogous situation, which would mean that they aren't really adopting a fundamentally different approach to reading. Their 'reading program' still takes the same shape as normal people, only a component of it is outsourced and so is no longer consciously available.
Incidentally Charles Dickens wrote about Laura Bridgman (the first deaf-blind person to learn to 'speak' English by communicating with her fingers) and said you can literally visually tell when she's thinking since she'd be moving her fingers. That sounds like the analog of subvocalization for her.
> Her social feelings, and her affections, are very strong; and when she is sitting at work, or by the side of one of her little friends, she will break off from her task every few moments, to hug and kiss them with an earnestness and warmth that is touching to behold. When left alone, she occupies and apparently amuses herself, and seems quite content; and so strong seems to be the natural tendency of thought to put on the garb of language, that she often soliloquizes in the finger language, slow and tedious as it is. But it is only when alone, that she is quiet; for if she becomes sensible of the presence of any one near her, she is restless until she can sit close beside them, hold their hand, and converse with them by sign.[20]