I think complexity is definitely part of it but it is also mis-aligned incentives. The person running an assembly line has a vested interest in changing nothing

I think complexity is definitely part of it but it is also mis-aligned incentives. The person running an assembly line has a vested interest in changing nothing. Everyone knows how it works and consistency sometimes is more important than raw efficiency. If they change something and if breaks the machine or they have a month of lower productivity, they don't get a promotion and/or bonus. Why would they risk it? Plus, people generally hate change. You actually have to have someone whose job it is to look for inefficiencies. Someone who goes and talks to everyone on the line because they are the ones that really know. Someone who also recognizes that a 5% improvement in one area may not be worth the risk but a 1% improvement somewhere else may be. Just like staff scheduling: do you schedule the bare minimum of staff? What happens when 3 people next to each other all get the flu? Now where are you? Are you better off normally over-staffed and constantly cross-training? Most companies make money despite their operations. This is where Amazon has taken over the world, they have that as a core goal and corporate focus.