I didn't leave the other variables out. A human in the loop doesn't change grind size or consistency. A human in the loop doesn't change water quality, or temperature. A human in the loop won't change bean quality.

Tamp pressure is more consistent with automated machines vs humans. It is much easier to dial in a shot for particular beans/roast, you can literally dial it in, that's why coffee shops use automatic machines. Those machines are not the cheap ones they can cost up to $10k. Over half the coffee shops in my area use automatic machines.