I think data transfer is a big issue. Even at Google's scale, 10 petabytes a month (10 million android users) probably creates more costs than it's worth for th

I think data transfer is a big issue. Even at Google's scale, 10 petabytes a month (10 million android users) probably creates more costs than it's worth for them. It's much easier to compress data on the device and only send new information, with that you can easily get a month of location history <10mb even for people who move a lot.