True - and an important distinction. Hiring someone for $20/hr to sit in the cab of some multi-million dollar harvesting machine isn't that hard.
I think it's a bit of an area that doesn't really benefit from more efficiency (except on the things that have to be picked by hand) - farmers don't even bother flattening their land to make it easier to plant/harvest, as the machines handle slopes and hills just fine.
I agree it is an area that we have probably already reached peak from labour efficiency stand point. Ofc, machines can get slightly bigger and methods slightly more optimised. But there is good reasons to keep a human in loop and near to fix any immediately fixable problems. Or just to fill fertilizer or empty the load.
The farmer is the person doing the hiring (or, rather, on behalf of whom the hiring is done, whether directly or indirectly.)