> I never understood the value proposition of Apple Maps.

They ship their operating systems with all the "common" apps pre-installed (e.g.: Email, Calendar, Reminders, Notes, Maps, etc). For the maps to work, they need some data source. That's what Apple Maps is.

Apple doesn't make money with the Email app directly, but its existence likely improves how users perceive iOS. This probably translates to return customers and more people recommending it.