"its always Korean or Asian kids on MN that are tutored"
Sorry but many kids in Korea are tutored. It would be quite hard to avoid the prevailing culture even if you were white and middle class. I used to live in Asia and this was a standard concern of expat colleagues whose children were at local international schools. Should they simply let their DC drift to the bottom of the class, or should they join in the prevailing tutoring culture, even though they were not happy with it.
I cannot see why you should suggest Korea has a different approach to education is akin to racism, and that is how I am reading both posts. I can't be the only one who considers using accusations of racism to shut down debates is boring and lazy. I was specifically countering your assertion that all kids in academic private sixth forms are tutored, by suggesting that virtually none on my DCs friends were. And of the two they knew did receive extensive tutoring, one, a boarder, was from Korea.
I appreciate that your DS may be at a different school. Certainly maths was a strength at DCs school and DS was able to achieve an A* in Further starting from the sixth set and without any external help. I can understand the need to bridge obvious gap. DD is dyslexic so English GCSE was a challenge. But I still don't think it is the norm for selected children to need on-going tutoring. Unless, of course, they were tutored in order to perform well in the entrance exam. There are lots of other things teenagers can be doing like scouts and ballet (or gaming) which will contribute to breadth as opposed to just grades.
There is also a danger that tutoring becomes a sort of prop, allowing a child to drift through class because they know that they will go through it again one-to-one with a tutor. There is a real benefit with maths in particular, for classmates to support each other when things are not clear, as this is what they will have to do at University when vast amounts of content are covered in a single lecture.