I know that in Europe graded repertory is essential to their way of pedagogy, with tests that you pass in order to advance to the next level. In the USA we don't have these specific grades of music performance. I kind of wish we did, but on the other hand, it is up to each individual and his/her private teacher to study the appropriate repertory. In universities around the USA, each studio has a syllabus (a set of course requirements and repertory) that is sometimes graded. In my studio there are specific repertory levels. You must be able to play certain KINDS of repertory (with some specific titles here and there) at certain levels of expertise to advance to the next level of study.
I really have no opinion about the repertory that Europe chooses for its grades, except that it often does not include very challenging stuff, and almost no modern (written now!) pieces. I know I am gonna get flack for that comment!
Hope this helps.