>The problem is that a high school education represents literally years of knowledge a person has accumulated.
A high school diploma only signifies the individual was approved by the indoctrination of public education, unless you're the handful that had private or homeschooling which still doesn't mean much academically (see below).
Incidentally, in the US we have what's called the GED[1]. The GED can be taken at any time without any requirement for prior education, and passing the GED is equivalent to graduating high school.
So no, a high school education in the US does not represent "literally years of knowledge".[2]
[1]: https://en.wikipedia.org/wiki/General_Educational_Developmen...
[2]: I'm a GED graduate, and I can tell you its contents are roughly equivalent to elementary schooling in most other countries. I can also tell you that is what a high school diploma represents in the US, academic wise, because they are the same. If you can calculate 1+1=2 and speak basic English, you are an American high school graduate.