Your accomplice would have to take possession of the phone at a comfortable distance from the target bank. (Again, in a place that no one, and no camera can observe the arrival of either party.) And the co-conspirator actually robbing the bank would have to make his/her way to said bank without being observed leaving the phone drop site. (And without being observed traveling in a direction inconsistent with his/her phone's location data.)
All of that is not as easy as it sounds. One traffic camera on a stoplight and they got you, in your car, heading towards the bank, in the opposite direction of your phone. Now your co-conspirator is in trouble too. (Aiding and Abetting at minimum.)
We're creeping towards an age of ubiquitous gaze, and only people who are way smarter than I really know if there's any averting it at this point. I think the only real defense against ubiquitous, 24/7 surveillance right now is to live life in a remarkably unremarkable fashion.