Because the setup is still too complicated. This will probably take off once Amazon finally gets robots that can do unboxing, picking, and boxing. They've been

Because the setup is still too complicated. This will probably take off once Amazon finally gets robots that can do unboxing, picking, and boxing. They've been trying for years to get that to work. Amazon already has robots doing most of the lifting and carrying, but people still handle each item. People have been trying to do bin picking fulfillment with robots since the 1980s. Swisslog, Brightpick, and Universal Robotics have all demoed this, but so far it's not working well enough to take over. It's getting close, though.