Meeeeeeh...I dunno. Passing a class is more than memorizing facts and figures. There is an element of functioning in a society, too. Would you want to hire a straight-A student who doesn't show up for work or do what they are told, even if they understand the job? Would a college want to accept a student who is not prepared for the most basic requirements of lab work?
I mean, a public education is more than just the three Rs, isn't it?
I've employed hundreds of people over my years, never once did I think an "A" grade or a "1" etc. in a subject told me anything about their attendance or their behaviour and so on as a kid at school or even college and university, it told me about a sliver of their academic capability. If the USA is using academic grades as a proxy for attendance and behaviour that seems very strange to me as I can't see any way a prospective employer can "decode" what that grade meant. Are they thick but turned up for every lesson, are they intelligent but only turned up for half the lessons, are they average but disruptive in class? How do you work it out?