s/us/your phone, that we control the software for/
I believe this learning is done on-device, not relayed to the cloud.
Depending on whether you take Apple's statements at face value about how much they care about your privacy, that's either a big difference or a meaningless difference.
I doubt that figuring the places that you frequent is computed on your phone. Most likely it sends your locations and then Apple runs hadoop jobs (or whatever it is used these days) to get these things.
