1) In Europe if a student is bad and fails several subjects, he has to repeat the year.
2) In HK if a student is bad he is put in a lower band class. In my daughter's school there is A, B, C, D. D is the worse, and is made up of students who fail in many subjects.
With the HK system, students pass, but then the worse students go to Band 3 schools, can't go to university, and are destined to manual works. Basically from primary school your life is set out for you, and this is why you have so much emphasis on private tutoring, to try to avoid your primary school kids to go into C or D classes. But then it's just a rat race, since the worse 50% will go to C or D. You might have quite clever children also in C and D. But they are still destined to band 2-3 secondary schools, and manual work with salaries barely sufficient for survival. The only way for a not-smart kid to go to university is to have rich parents and do the degree in another country.
With the European system, students fail and repeat the year, but then they have a shot at doing well in subsequent years. Also, since smart and less smart students are together, smart students pull the less smart up.
I guess at the end the HK system is better for very smart kids, who can educate themselves faster since they are surrounded by equally smart kids. On the other hand, it's a horrible system for stupid kids, which robs all chances for upward social mobility. Money may contribute for some lack of brains (e.b. buy paying a lot of tutoring or foreign university), but for a sizable proportion of HK kids (the poor and less smart) life is destined to be quite brutal.