I generally agree with your sentiment for improving education, but I don't think the limiting factor for ATCs has to do with it, but with innate qualities in individuals.

You can see the list of criteria here: https://www.faa.gov/air-traffic-controller-qualifications

- Be a United States citizen

- Be under the age of 31

Well, they restrict the pool pretty harshly right from the start.

I think most people underestimate the amount of "innate qualities" from patience to creativity etc. that actually are influenced by education, parenting, etc. rather than being defined at birth by genetics.

Education isn't just about changing the quantity of knowledge people have learned - a country with good free education, along with other things like mental health support, good parenting resources/education/support, etc. will lead to more people having the qualities needed to be ATCs despite not having learned them by going to specific "managing stress 101" classes.

(Edit: It's possible I misunderstood you and by innate qualities you literally just meant the things in their explicit requirements list like being under 31 and being a US citizen, if so apologies but I'll leave my comment here anyway.)

A quick google suggests that only 35% of US adults have 20/20 vision (although I guess it might be higher if you restrict to the population of the age required) which is one of the requirements so that by itself limits the pool of applicants significantly regardless of education, parenting etc?

I don’t think being a good applicant for air traffic control has a lot to do with classical education. It demands a lot of stuff you don’t really need for university, and a lot of experience and education in university won’t make you a better traffic controller.

Once upon a time in a country of the Universe some wise leader decided that there should be twice the number of graduates than before, so they made the education more accessible, accepting twice as many people than before. However, one - evil and ugly - department in the unversity was a barrier. They failed much more students than before with their old and ugly exams, so with some convincing they improved their exams reducing the level of expectations and voila, there were much more graduates designing buildings and other critical infrastructures than ever before, everyone lived happily ever after.... ?