The German soda market is very very regionalized, along the same lines as the beer market (20 to 50km around the brewery, further away you won't get it anymore. Very big brands are exceptions of course). Practically every brewery (there are over a thousand) has its own line of sodas, usually white (lemon or lime) lemonade, yellow (orange) lemonade (both carbonated around here), spezi (cola plus orange), cola (some coca cola copy) and apfelschorle (apple juice plus carbonated water).
Additionally there are a few that cater to certain groups with special products like mate soda (Loscher invented it with Club Mate I guess, but nowadays there are 10 big brands and a few small ones) and special kinds of cola like AfriCola or Mate Cola. Fritz-Kola is one of those products, you can get it in every city in well-stocked supermarkets, but it is a product that only caters to a certain kind of people and establishments (think "Berlin-like club-going techno-mad party-crowd" maybe). So many places will carry something else that caters to their group, and their region.
That is also why the Coca-Cola marketshare that the sister comment mentioned will go down, but it will not be replaced by another big producer, just maybe a handful of nationwide brands plus tons of regional ones.
Additionally there are a few that cater to certain groups with special products like mate soda (Loscher invented it with Club Mate I guess, but nowadays there are 10 big brands and a few small ones) and special kinds of cola like AfriCola or Mate Cola. Fritz-Kola is one of those products, you can get it in every city in well-stocked supermarkets, but it is a product that only caters to a certain kind of people and establishments (think "Berlin-like club-going techno-mad party-crowd" maybe). So many places will carry something else that caters to their group, and their region.
That is also why the Coca-Cola marketshare that the sister comment mentioned will go down, but it will not be replaced by another big producer, just maybe a handful of nationwide brands plus tons of regional ones.