We’ve got one of the most educated populations in the world. Europe is only recently catching up to is in e.g. the percentage of people with college degrees.
I don't have many vivid memories of my primary school education but one of them was being taught how to be suspicious of claims made in advertisements. That one class stuck with me for a long time. (This was in Melbourne, Australia sometime around 1988.)
Turning your descendants into doctors and lawyers is one of the traditional ways families use to preserve their wealth. It isn’t because these people were smarter.
FWIW, advertising and to a larger extent advocacy in 1988 and what is today are entirety different animals.
Though I do agree with your point. The number of college graduates does not equate to higher critical thinking of a nation's populace.
I did attend a journalism class almost a decade ago. Even though the powerful effects of mass media on people were likened to a magic bullet [0] It would be correct to assume that social media tech today has transcended this very capability and in more powerful ways than ever imaginable by its inventor.
There certainly are more forms and techniques of advertising, but if you teach the fundamentals sufficiently well, the critical thinking skill set can adapt as advertising adapts.
An important fundamental is to recognise that you have a desire for a product or service and to know to be conscious of the chain of events that have led to that desire.
Even if everyone experiences the same schooling, everyone isn’t going to be equally educated.
Keeping children in school for 12 years doesn't mean they are educated.
Keep in mind that between 7-9% of school-age children in the US are homeschooled.