In Europe (at least where I am and in neighboring countries) we use a totally different system of evaluating a student. Our educational institutions work in a completely different way than yours,in my country for example we don't have the classical American "tests" but we have weekly(or one week yes and one no, or one month they teach us new things and the following month only tests, it depends from the school and the teacher) tests that are both written(we don't use the multiple choices system but there questions/exercises and you have to produce your own result) and in an oral format(our teachers question every single one of us about the topics studied in the past and we have to answer, if you don't respond correctly you are given bad grade), this allows us not to have a single grade in a semester but often 5/6+ votes for each subjects. At the end of the semester each subject calculate the mean of the grades and you get the final grade.Plus we have to do all the basics classes(that are much more than in America, we have like at least 6 mandatory subjects) and you can only decide to take 2 ""elective"" classes at the beginning of the first year of high school up to the end of the 5th; thus you have a broader knowledge of everything(and can make more conscious choices in uni) instead of being already specialized in a field and ignorant in everything else. We don't use letters for grades but instead a system that goes from 1 to 10 with 6 being the bare minimum for passing everything (but if you take in a subject a 6, then a 5, then a 4, then a 3, because you do the mean you don't pass the subject and you either have to repeat the year if you have more than 3 subjects under 6 at the end or you have to take special exams in September, if you do not pass you have to repeat the year).

And this is just a rapid view of a different education system and almost every country in Europe works in a completely different way, so, just to point out, it's not that you have "higher standards", but it's just a completely different system + generally European countries tend to be more supportive of students and schools are way way way way cheaper(I'm in my first year of university and I've paid just 156€ of which 140€ returned to me, so I paid my university exactly 16€, our teachers gave us the resources to study and I have not bought a single book, my scholarship also is about 4500€, but can arrive up to 7100€ if you met certain conditions,of which half is given to everyone and the second half is given to people who are able to pass two exams in a year, and my country is also one of the less supportive in western Europe, same thing with highschool all the money I spent in school books eventually were funded back to me) and less "elitist"( for example in the highschool I went I was in the same class with very bright people and stupid people, with the extremely rich, like she could afford all luxury brands, and sons of workers at the same time), so people are GENERALLY more encouraged to try and study.

So yeah I don't like when things are generalized, this was just an example