Wikipedia happily reports that North Korea has a 100% adult proficient literacy rate. Cuba has a 99.9% rate. Brazil 98%, all leaps and bounds beyond any western country. https://en.wikipedia.org/wiki/List_of_countries_by_literacy_... The US is certainly behind much of the world in education, but these metrics are really hard gauge accurately. Diving in to where these numbers come from and how they compare to the rest…
A somewhat similar study is the 2016 OECD report (based on a survey conducted in 2011--12), "Skills Matter: Further Results from the Survey of Adult Skills "
https://www.oecd-ilibrary.org/education/skills-matter_978926...
Jacob Nielsen addressed that in the context of computer UI/UX requirements for general-use application and website design, "The Distribution of Users’ Computer Skills: Worse Than You Think":
Across 33 rich countries, only 5% of the population has high computer-related abilities, and only a third of people can complete medium-complexity tasks.
https://www.nngroup.com/articles/computer-skill-levels/
I've referenced both in my own essay, "The Tyranny of the Minimum Viable User", which acknowledges both that general-use systems must be generally-usable, and that this requirement reduces functionality for advanced users by numerous mechanisms.
https://old.reddit.com/r/dredmorbius/comments/69wk8y/the_tyr...