Ah just like with the "PhD student" joke in another thread: the value is likely in the "workers compensation case" savings when you can show that you did everything humanly possible to mitigate risk of injury, should there be a claim

Yep. Even in the linked video around 3:20 the assembly makes a short 3foot trip on a conveyer. There's a cut there but you could imagine instead of walking the part that distance and back now they have half the next item already done. Looks like some are used as a small queue for the next station as well to give some slack to timing variations.