If I read
"Computer programs are available to help instruct speed reading students. Some programs present the data as a serial stream, since the brain handles text more efficiently by breaking it into such a stream before parsing and interpreting it."
and then turn my head away to describe what I've read, I say: "computers can help in speedreading, because they can show data serially and it's better for the brain that way", but never remember how it was written (I didn't even remember the "instruct [...] students" part).
I've heard of actors than can memorize what they read almost immediately but they actively want to memorize the text. It does not happen automatically.
I like most people remember the jest of what I read or hear. Every once in a while I remember text verbatim. It usually has to do with how impactful the passage is so I tend to remember it. It's never very long.
Remembering everything sounds good but that means you'll have to remember both the good and the bad. Imagine remembering all your bad experiences forever. It does not sound that good.