it probably doesn't help that the US education system is so deeply broken with how rooted it is in segregation-era practices [0][1][2]. the average gets dragged down quite a bit when some districts receive so much money that they're flying their Spell Bowl teams to nationals and putting them up in hotels while another one a few miles away can't afford to pay for textbooks. average reading levels suffer and consequently so too does the effort that people put into writing well and reading critically
[0] https://www.shankerinstitute.org/segfunding
[1] https://www.jchs.harvard.edu/research-areas/working-papers/s...
[2] https://edlawcenter.org/research/the-color-of-opportunity/