Re: A really confused Yank here
"Here, you need a minimum number of English, Math, Science, Art, and what we call Social Studies (civics, history, economics, etc.) to graduate."
Those mirror the requirements in a Scottish Standard Grade pretty well, at least at my high school. English, maths, a social science, a language, a science and an art were all required, leaving two timetable slots to fill with other subjects. Standard Grade takes place in the third and fourth years of high school (we have 7 years of primary school and 6 years of high school), before we take Highers. I believe your perspective is skewed slightly by the fact that the article discusses Highers and A-levels almost exclusively, at which point some specialisation kicks in (to a greater degree south of the border).
Students that decide to leave school at the age of 16 (after completing Standard Grades, usually) almost always go on to study a vocational course at a further education college, so it's not like they're dumped out of the education system at that point.