> A lot of mechanisms are involved. Culture doesn’t just impact the scores people rate something on, but also how people interpret them which mitigates that effect.

It doesn't mitigate the effect, the combination of the effect on rating and interpretation is the source of the issue, which exists whenever the review reader isn't in the cultural midpoint of the raters.

> whenever the review reader isn't in the cultural midpoint of the raters

Obviously, yet the scale of the mismatch when looking at a composite score isn’t total, thus the effect is being mitigated.

Further, even without that the more consistent the cultural mix the more consistent the ratings. Anyone can understand a consistent system.