As one of those people most of the time (communicating with other people is the main exception), I still find it astounding that it's hard for some people to understand.
Take riding a bike: I presume even people with an overactive inner monologue aren't constantly planning their actions (brakes, steering, turns) in words. Then just extend that out to most other stuff.
>>chongl+kj
That's how I start reading, but once I'm really into it, no - I'm seeing a (low-quality) version of the scene in my head and not even registering that I'm still reading words and turning pages.