At one point in my life I was an inspector in a machine shop.
I went to a tool show in Chicago with the plant manager and got to listen while sales people tried to say that these new Cnc Swiss turning centers were so accurate that you could just load them up with bar stock on Friday and let them run all weekend with the lights off and Monday morning you would have barrels of good parts
In the real world tools get dull and then break
and then you have to pay somebody to sort and put scrap parts in a separate container from the good parts. Then somebody else has to make a judgement call on parts that are only a little bit out of spec. Etc, etc.
