> The U.S. scores are interesting.

Unfortunately, those scores are not reliable. It is a recurring problem with the USA for the PISA studies.

The preliminary chapter explains why data has lower confidence is some places. For the USA, there were many problems, including political reluctance in some states or schools, that lead to uncontrolled biases. Notably, the ratio of unreachable children is 40 %, twice more than their upper limit for valid results.