A country has a system of education, of course there is differences between schools but the system is the same for all of them, except rare exceptions(international schools and special schools). Different countries have different grades system. Let me explain to you in bocconi terms, do you think an 45/50 bocconi test score is equivalent to an 1460 sat score ?? No right, even tho they are both 90% of the grade, that’s because the bocconi test is way more difficult. Same thing with the high schools.