I used to design and build high speed packaging machinery. When I started my apprenticeship in the late 90's I saw machine lines running at 6000 units per minute with 3-4 operators per line and regular maintenance performed by a team of skilled engineers. Mid 2000's it was 10,000 units per minute, 2 operators per line and periodic maintenance performed by a skilled engineer. In 2012 I visited a factory with row upon row of machines running at 20,000 units per minute, fully automated lorry loading for dispatch and the machines diagnosed their own preventative maintenance. There was a guy wandering around with a broom. Two years later I jumped and changed industry.
Looks like each time they took a person out of the loop the machines got faster, and the factory increased in capacity. I think this is the true benefit of automation. The cost reductions from 4-1 operators is pretty minimal. The increase from 6,000 units a minute to many lines with 20,000 units a minute is where the money is.
Quite right. The production facilities do tend to shift to less expensive regions for labour too though, which does increase the impact. The first factory was in the UK, the second Poland, the third was in China. The UK one doesn't exist anymore.
But thats because you are only looking at it from the perspective of the parents example. Now extrapolate further and keep some of sort accelleration in mind and you will see that the next step which is cost reduction from 1-4 factories.