Your assessment is probably closer to the truth. 54% of American adults have a literacy below sixth grade level link and some of the people you’ve met probably are considered barely literate yet counts towards the 79%.
A curious statistic I’ve found while reading up on this is that 77% of African Americans have moderate or high reading proficiency while only 65% of white Americans qualify as such. A statistic that you’ll never see racists mention (and libs for those that somehow fit outside the venn diagram)
I haven’t done any research on this, but my gut says it’s because black people are more likely to live in urban areas with at least the basics of public education. Whereas white people comprise more rural areas. Not saying living in a rural area makes you illiterate, like I grew up in a small town in the woods, but it does mean there’s just less of everything, including education. More homeschooling too among white people.
Could also be that white people take education less seriously because they don’t feel threatened by a hostile job market. Did your readings say why there’s a disparity between demographics?
It was just a cute factoid that I noted, so I didn’t look further into the claims.
Your theory could be correct. Another reason I suspect is that due to racial biases and different job market situation arising from the urban/rural divide, black Americans are forced to be more literate in order to survive compared to the average white American.