Well-rounded People
The American educational system seeks to turn out "well-rounded people". Such people might have specialised knowledge in some area, but they are all expected to have a general acquaintance with many disciplines. Having passed through a system that requires them to study some mathematics, some English, some humanities, and some social science (and perhaps a foreign language), they presumably have an array of interests and can understand information from many fields of study. Thus, specialisation in the American system comes later than it does in many other systems. Students are required to take courses that they themselves might not be interested in and that might not have any apparent relationship to their career aspirations.
Although not an "ideal", there is a final sentiment that must be taken into account as one tries to understand the American educational system. That sentiment is anti-intellectualism. Most Americans are suspicious of theorising and "intellectualizing". They want to see practical results from time and money spent. Secondary school and university graduates are expected to be well-rounded to an extent, but not to the extent that they cannot do anything "useful". Americans are unimpressed by most learning that is done just for the sake of learning. They have no general reverence for university teachers who live in an "ivory tower" that is divorced from the real world.
Social Forces Affecting American Education
A few aspects of the social context in which American education operates are worth mentioning. The first has to do with the social status or degree of respect ascribed to people who are involved in education.
American teachers (that term usually applies to people who teach in kindergarten through grade 12, the final grade in secondary school) do not enjoy high status in the society. Respondents to a recent Gallup Poll placed teachers well below physicians, clergymen, and bankers in terms of their prestige or status in the community. Judges, lawyers, and public school principals were also rated above teachers. Funeral directors and local political office-holders were seen as having nearly as much prestige or status as teachers did. Teachers are not well paid. Their working conditions are usually less comfortable than those of workers in many other areas. They are not as well respected, as are people who actually "do" something rather than "just" teach.
Nor are college and university professors generally held in the high regard they are in many other countries. There are some exceptions - mainly those who have made particularly noteworthy contributions to science (not the humanities, usually, because the humanities are not "practical") - but professors are often viewed as people who are teaching because they are not capable of doing anything else.