The last decade also taught me that segment of the population is a lot larger then I expected.
It was quite eye opening to learn how many of my countrymen are proudly unethical and illogical.
Much of that has to do with the US’s high immigration rate, many of whom are not native English speakers. If you open the map your source links to and look at the lowest levels of literacy, they are primarily either places along the southern border, places that host a lot of migrant labor, (like California’s central valley,) or impoverished regions of the country, (like parts of LA and MS.)