Experiment. Take a 'basic' piece of knowledge, oh I don't know, let's say the fact that the Moon revolves around the Earth. Where did this knowledge come from? And how widely dispersed/propagated is it through, umm let's say the population of France?
Who wants to be a millionaire clip
To summarise, the guy is asked "Qu'est-ce qui gravite autour de la Terre?" (What revolves around the Earth?), The Moon, The Sun, Mars or Venus. He answers The Sun after an audience poll yielding 56% for the Sun, 42% Moon and 2% for Mars.
Those numbers need qualifying and cleaning up a little. First up, we have to consider that more than 58% didn't actually know the correct answer, there may have been some who did not know and just picked an answer at random, some right, some wrong. Note however that the quizmaster says not to feel obliged to answer. On the other hand there is pressure in situations like this to not look stupid - so you just press a button anyway (potentially).
I also just want to address the more pedantic readers out there in internetland - it is of course more correct say that the Moon and Earth rotate around their common center of gravity(barycenter), but that center is within the body of the Earth and so it's not an unreasonable question to ask in a general purpose quiz. OK? Certainly this guy wasn't struggling trying to work out what is meant by 'revolve' - does that word have a different meaning in real space-time than in Euclidean space? hmmm.
So anyway, at least 58% of that audience were not in possesion of this particular piece of knowledge. It doesn't appear to be a core, commonly known fact in French society (and mostly likely others), like say 1+1=2 (this is an assumption). And yet there is this large shimmering, fairly prominent silk cresent in the sky. It wouldn't be unreasonable to have assumed that most people would have looked at it at some time and wondered what it was and made enqiries. Consider this versus some obscure fact deep in some specialist research paper, why would most people know about that? What would the hook or lead be that led them on an a path of enquiry to it? The path to the fact is more tenuous and arduous and therefore we could expect most people to be oblivious to it.
So what is it that determines which pieces of knowledge become widely known, given that the moon is misunderstood despite being so prominent? Most probably it comes down to the fact that a given human's primary purpose in life, whether they know this or not, is to propagate his/her genetic makeup into the future. Learning all of this pesky knoweldge stuff is just a necessary cost of achieving that goal, and the knowledge that assists most on that quest is that related to society - it's structure, who has what power and skills(rather than aquiring all of the skills yourself), who to trust, and of course evaluating potential mates - in the traditional sense of the word :)
We are bombarded with senory input conveying vast quantities of information from which we could infer and deduce vast quantities of knowledge if we had the time and perseverance, but doing so would be sub-optimal with regard to the task of propagating our genetic sequences into the future. We are programmed to notice some features and to think about some aspects of the physical world moreso than others.