However, high school course selection is still oriented toward “general education” in that high schools themselves tend to specify a substantial percentage of the curriculum in graduation requirements (English, math, etc.), and non-open-admission colleges generally expect some baseline of high school course work for students to be prepared for college work. While a high school student can explore and develop interests, s/he may be limited by both the amount of elective space (after filling up much of his/her schedule with requirements and courses expected by non-open-admission colleges) and by what the high school actually offers.
Opportunity for academic exploration tends to be much greater in most colleges*, since students typically choose majors of their interest, and can choose in-major and out-of-major electives for a much larger percentage of their courses than the percentage of electives that they had in high school. The breadth of course offerings is typically much greater in college than in high school.
*Yes, there are a few exceptions where most of or the entire curriculum is specified (e.g. St. John’s College) or where the school is small and/or highly specialized (e.g. Webb Institute, Embry-Riddle, maritime academies, Babson).