I can only speak from experiences in American School Systems. Historically American Education was somewhat based on Piaget's theories of 'readiness'. So, by first grade one should be ready to do addition and so on up the years in each subject. If a student was not ready for a new grade they got extra assistance, summer school, or repeated a grade (Of course this was not necessary in the one room school houses, I digress.)
After Sputnik was launched in 57, American educators felt their ed. was inferior, took a new perspective, and "pushed down" higher learning to lower grades. Also by the 60s, more Moms were working out side the home and childcare centers became preschools and attempted to teach 'grade school subjects' to toddlers. I happened to have been in one of the middle school research math books in the 60s that taught 99 percent theoretical math and hoped to prepare everyone to be a computer programmer or astrophysicist. That math book series was quickly scrapped. Because an A in a specific school-to-school meant something different, there were entrance exams to post secondary schools.
Of course, individual students from the same school got a range of scores, and this did not affect non college bound learners. Many big businesses had to take a new employee for many months to train them in basic skills that they lacked although having a diploma. For some years, there have been state-wide initiatives (after funding many dollars to groups of educators to come up with grade level expectations. I was one of the unpaid persons who worked on this in New Hampshire.) So, many states have come up with expectations called "learning results, common achievements, standard assessments, et al."
Enter: NO Child Left Behind - through this policy, students would graduate whether they had any academic performance level or not, hence the I.E.P. (Individual Education) diploma, which is generally useless in the job market or vocational schools. IEP students had to go back to school for a GED or High SChool Equivalency Diploma. Some of these student had not had any expectations since third grade. So, University of Massachusetts (where I went to college) worked on a series of tests that went from pre-literacy through high school graduation level, called the TABE (TEST of Adult BAsic Education). Although this test is not perfect, and is generally not used (by educators) according to its own instruction, it does place a student of any age into a distinct grade level (in each subject, which can be five different grades), with observable outcomes through post testing. It could rightly be called 'test for basic education.'
NOw, the up and comer, Common Core. It is true that there should be a common expectation for each subject, each grade. I only retired 9 months ago, so was on the ride for its roll-out. The teacher workshops I attended and materials recommended were abyssmal. The "text books" were fraught with error, did not match the work books or answer keys, and were constantly being re-called. Teachers were arguing with each other during the sessions.
Primarily, though, the problem is behavior in classes, and the idea that there will be a "teachable moment." There are few, and so many admins are looking askance at student cheating or grade inflating. In the case of one-on-one aids, the assistant is frequently doing all the work. They are even allowed to sit with their student during testing, or students are allowed to take their exams out of the classroom into resource rooms, where the exam can be read to them, someone else can write down the answers for them, and so on.
HOmeschooling is one alternative, and there are 'typical stated curriculum' goals available which many home-schoolers enter on their letter to their school admins. Unschooling is a philosophy of some homeschoolers which minimizes formal attempts during home education.