I think it's kinda like Google working with Android as an open source project. Google makes money on Android primarily by using Android as a means of delivering the Google ecosystem. They don't care that it's open source because they don't make money by selling it.
Apple could do the same thing with maps. Support a robust open mapping initiative to make sure their primary business (selling iPhones and other devices) has a solid platform for emerging technologies like AR. Making sure they have a solid maps offering supports the Apple (aka iPhone) ecosystem.
Also similarly to Google, they can still push plenty of proprietary things on top of the open parts of the initiative.
Apple could do the same thing with maps. Support a robust open mapping initiative to make sure their primary business (selling iPhones and other devices) has a solid platform for emerging technologies like AR. Making sure they have a solid maps offering supports the Apple (aka iPhone) ecosystem.
Also similarly to Google, they can still push plenty of proprietary things on top of the open parts of the initiative.