The main problem seems to be atrophy. In this specialized age, Johnny's folks spend more than half their waking lives at limited and repetitive jobs, learning little beyond a narrow skill set. Throw in dinner and "Must-See" TV, and it's no surprise that the Jefferson of the modern age is George, not Thomas.
The study, which rated Swedes most "literate" and Poles least, also cited America's high dropout rates as a contributor, but noted that education was no guarantee that an American adult could handle tasks like deciphering a bus schedule or calculating the interest on their mortgage. Isn't there a computer program that does that?