That’s rather indirect. But you do have a point.
However we do know quite a bit about those events? So any English speaker who cares can learn about them.
> How much effort do they typically devote
Well unlike illiterate societies they don’t need to because of books.
> massively less historical knowledge despite that effort.
Well obviously, we can’t really compare them with more literate societies. Then again we’re just very lucky that there was no complete societal collapse in the Greco-Roman world since the 500-600s BC. or so. Some highly literate civilizations like Carthaginians or the Etruscans were effectively entirely erased because nobody bothered to copy their texts).
The problem with oral traditions is that they can preserve knowledge of events that might have happened > 500 years ago (e.g. Homer describes cities, weapons and other aspects of pre Bronze age collapse Mycenaean civilization but it’s all intermixed with contemporary(Greek dark age) stuff and it’s very hard to separate fact from fiction (even ignoring the supernatural bits).