That is an overabstracted viewpoint that assumes they just crank up a variable. How do the efficiency gains take place in the first place? By creating somethin

That is an overabstracted viewpoint that assumes they just crank up a variable. How do the efficiency gains take place in the first place? By creating something new that is more efficent. Even if we ignore economies of scale as a source of efficency there is a replacement curve in action which would create growth! A situation where they would immediately scrap the old equipment for the same payload and switch to a new more efficient one is extremely rare.