You read a text. Then, you are asked a series of questions to assess your reading comprehension. Rinse and repeat for a school year to get a solid idea of each student's proficiency.
This skill has been declining steadily since the 1970s, but the decline has accelerated since the mid 2010s. Eventually the productivity boom should take a hit when newer generations struggle to understand basic tasks and the older generations retire. AI is probably orthogonal to the solution space.
my point is that evaluating reading comprehension is typically done as a test, and test taking is not a valuable skill
the evidence is that individual workers are more productive than ever, and this trend has continued since long before the 1970s. this is despite any measured decline in reading comprehension
the older generations are obviously not propping up the world economy through their singular reading skills