It depends on what kind of map you are building for which use cases and how passive you want it to be. Sure, you can use an iPhone or Android device but its not very passive (requires starting up, etc.) and it will quickly overheat when it gets hot. We tried it, and most people gave up after a few weeks given the fact that its not passive.
For most commercial fleets there is real value in the services we provide, eg monitoring, accident detection, remote video retrieval in case of accident, ELD compliance, etc.
You should read the article about rewards/incentives as it talks about that.