You are right, Larry, it's irrelevant.
Doubly so because motor skills are related to everyday life far more than to Olympic sports, and also because the post about US athletes/states is based on no knowledge whatsoever. The point of allowing time for fine and gross motor skills is that students are allowed opportunities for movement and for skill development, with academic skills introduced later at an appropriate age.
It's not true about no individual sciences until 15/16 years old though.
You start with the individual science subjects in freshman year of high school, at age 14, and do one each year. In middle school (age 11,12, 13, students do 'science' but with bio, chem and physics distinguished. The difference between middle school and high school therefore is the amount of time spent each week on each individual subject, not a completely general syllabus vs a specialised syllabus. In high school students do each subject every day - meaning a full year of one science subject. A sample sequence is one year each of bio, chem, and physics, followed by an AP level study in the final year of one of those three including Physics 1 or 2 (Algebra-Based) Physics C (Electricity and Magnetism), Physics C (Mechanics), or alternatively environmental science, computer science, or comp sci principles. There are also alternative science courses that are not AP level - offerings depend on individual schools. My local high school offers astronomy, human anatomy and physiology, a course in scientific investigative research, design and innovation, geoscience, and anthropology. There is also intro to engineering design, principles of engineering, civil engineering and architecture, engineering design and development, digital design and electronics, and computer integrated manufacturing.
Students in a remedial track have a different sequence and offerings.
The US offers two year degrees (aka Associates degrees) in community colleges. The cost is a fraction of the cost of the first two years of university. Credits can transfer to universities, where students can do their remaining two years and graduate with a Bachelors degree.
In England meanwhile students from the highest social class groups are three times more likely to go to university than those from the lowest classes. In the US they are twice as likely. There is a 46% gap in England between the 65% of students from richer families going to university and the 19% from poorer families. In America the gap is 36% while in Australia it is 32%.
www.suttontrust.com/newsarchive/uk-us-much-less-socially-mobile-australia-canada/
According to this article, it is actually the US that has a slight edge. Nothing to write home about though.