The statistics are that over 40% of Americans are functionally illiterate, and that another 25% are minimally literate.
You need to recheck your assumptions about American education.
A few minutes of research shows that your statistics are way above the generally accepted illiteracy percentages. The common numbers I was able to find are that about 18% of Americans are functionally illiterate.
That's not a particularly high number once you factor in immigrants and illegals who speak and read spotty English.