it’s really hard to prove that a candidate was rejected because of their ethnicity

Same in Finland at least to some extent. Statistics and published tests show that you’re less likely to get even an interview if you have a foregin sounding name but of course the official reason is always something ‘acceptable’. And when hiring people the reason can be whatever, “not good fit for our team”, “other applicants had better suited skill set”, “not enough experience in X” and so on. All perfectly good reasons to pick someone else in theory and in practise it’s impossible to prove any racism on selection.

Obviously not everyone does this and any of those can be a real reason to pick someone else even without any racism (intended or not), but it’s still common enough to be statistically meaningful.