> I’d much rather see Romania adapt a system which educates everyone, rather than the world be better at filtering.

Be careful what you wish for.

I understand the sentiment, and I wish we could make education as good as possible for everyone. The problem is, "as good as possible" is still very different for different people. So if you change the system so that everyone learns the same and no concentration of cognitive elites is allowed, it will mean that you have to really slow down the curriculum, to allow the average (and below-average) students to catch up with it. So the smartest kids won't get the best education they can get, and probably not even the kind of education they can get today.

> The kind of math we did in 10th grade (there are 12 grades in Romania) was math people were only introduced to in their first year of university in Denmark.

I suspect that this is how it probably happened. You were better at math then average, so you were allowed to learn faster than the average. The kid in Denmark who was your equivalent probably had to learn math at the same speed as the average Danish student. That's why they had to wait to learn that kind of math at university.

> There’re also a significant amount of optional after-school programs for contests

Yes, but it's still a huge waste of time if at school you have the math you already know, and you can only get the better math in the after-school activity; when you could be learning it at school instead.