A calculator used to be a human job. Are calculators smarter than humans?

I'm asking why is it reassuring about his job? Surely your big human brain can understand to be automated away doesn't mean the machine is "smart as a human" whatever that means. There is probably not a lot of utility in comparing synthetic and organic intelligence from such a reductive perspective.

Factory workers got automated by machines. Is a robotic arm smarter than a human? Is a tractor smarter than a bovine?

My question is simply what is he doing that is so "smart" or novel that it cannot be automated or mechanized. This should not be so hard to understand.