I'd be curious to know more about how they assure the same evaluation quality in different continents. I've been to several starred restaurants in Europe and US

I'd be curious to know more about how they assure the same evaluation quality in different continents. I've been to several starred restaurants in Europe and US, but I had VERY different experiences: the quality of food and service were on two completely different levels (yes, I read that's more about the food, but I'd still expect a certain quality when it comes to service as well).