Cost is one factor, but so is visibility. If we replaced humans following people around with cheap human-sized robots following people around, it would still b

Cost is one factor, but so is visibility. If we replaced humans following people around with cheap human-sized robots following people around, it would still be noticeable if everybody had a robot following them around. Instead we track people passively, often with privately owned personal devices (cell phones, ring doorbells) so the tracking ability has become pervasive without any of the overt signs of a police state.