I had to learn the hard way 15 years ago that the average American adult cannot parse a full-page email in standard English. It seemed crazy to me at the time and seems crazy to me now, given that the average adult has completed elementary school, but most people are barely functionally literate at all.
I don't expect you to believe me. It's a weird claim. But walk into any average grocery store and hand someone a page out of a book and ask them to read it out loud to you. Many people are so aware they can't that they will refuse to try. Of the ones that do, you will struggle to find one who can read the text with anything like the fluidity or inflection they would use to speak the same words. If you give them time to prepare, they'll probably be able to get through it in a few minutes, but nobody's putting that kind of effort into a text-only email, even if it's important for work.
Reading is so difficult as to be a chore for the average person. They don't just see written words and know what they say. They really have to work to get meaning out of written text.
With the proliferation of other means of taking in information, many of which require no effort of any kind beyond hitting play and staying within earshot, why would people choose to read? They didn't want to do it before. And now they don't need to do it either.
It's obvious if you think about learning a foreign language. Parsing written text silently is a completely different task than producing speech with the right intonations, even if you recognize the words.
Reading aloud fluidly requires a certain speed and anticipation. You have to be reading the next word in your head while you are still pronouncing the previous one. This isn't necessarily correlated with reading comprehension which is purely input.
The authority received the large body of text but, due to time commitments and attention, they didn’t have time to read it all. They used AI to convert the text to a concise bulleted list.