But the number of required service stations is also a function of how many customers you have and how they are distributed gographically, not only of how often they visit a station?

Surely you don't want people to drive 200km to the nearest service station, no matter if that's once a year or once every 3 years? Maybe that's the difference - customers expect EVs to be bleeding edge, so the service can be a hassle, and you can still get away with it?