How so? If the cost of making the computer able to do everything itself is greater than the cost of an equivalent system that takes human input, then you should use the human input version every time.
Also, humans are prone to error and many other inefficiencies. They get sick, quit, fluctuate in performance, require attention and care... you say "cost" like it's some easily calculable number, but it's a whole boatload of intangibles that just... disappear if the computer does it.
Also, humans are prone to error and many other inefficiencies. They get sick, quit, fluctuate in performance, require attention and care... you say "cost" like it's some easily calculable number, but it's a whole boatload of intangibles that just... disappear if the computer does it.