What we call "Market Groups" are an artifact of how we deploy our Product Read API. Any deployment can serve Product-Offer data (product with price and stock information from a merchant in a country) for all of our 29 European markets. But rather than have a deployment per country, or one deployment for all countries, we choose to group countries into 3 "Market Groups' named: eu-N. Our edge load-balancer interrogates HTTP headers to determine which Market Group deployment to send the request to, and we can dynamically adjust this edge routing as needed. The idea was to have some resiliency and be able to isolate say a massive sales campaign or bot attack in one country from impacting other countries. But it has been mostly useful for this staged deployment where we can deploy and test changes first in a group of our lower monetary value countries, such as Ireland, and then move on to higher value country groups, such as Germany/Switzerland. So not customers, traffic from countries.