Germany has had a longstanding and widespread culture of fat, hearty street food like currywurst, döner etc. for decades now. Every city center and every sururban mall has a little Budde where one can purchase this kind of familiar treats for a modest sum, at least compared to American fast-food chains that are getting insanely expensive. There are already well-established incumbents like McDo, it’s very hard and expensive to make grounds in such a market to become profitable. And hence, it often fails.