This is what you get in a long-established factory which, over time, gradually updates the weakest part of its process. The manual parts are either hard to auto

This is what you get in a long-established factory which, over time, gradually updates the weakest part of its process. The manual parts are either hard to automate, or are just so cheap to do manually that there's no point. At some point a human did the job that the robot arm does now, but then that became the bottleneck in some way. It was cheaper to get a robot arm than a human, or maybe there's nowhere for a human to stand on that side of the line, or maybe the human is just too slow lifting that much weight 20 times an hour. Edit: After having seen more of the video, that robot's doing a lot of heavy lifting (no pun intended). It seems to be doing all of the movement of the balls into and out of the various machining cells, and it's involved in quite a few steps of the production process. It's definitely paying its way.