I've used both hundreds of times in the US, and that has never happened to me. They would only call to sync our positions to find each other, which happened very rarely.
This is basically the same thing, except cancelling based on pick-up location instead of destination. The app apparently doesn't always tell the driver exactly where the pickup is- it only gives the direction to drive and the next turn or two. It only gives the exact location once they're close to it.
This is to keep drivers from cancelling based on an out of the way pick-up location.
When they call, it's almost always to get information that the app won't give them.
