A hypothetical example is drones going through a field and manually picking out weeds, increasing yield with the same amount of resources. Similarly you can get fine grained ‘crop analytics’ through drones scanning the field and acting in response.
I don't have any figures citations since my knowledge comes from when I used to hang out on Precision Agriculture forums, but it's common and getting more so. As drones get less expensive, it's easy to sit in your den and fly over the fields looking for the areas where you should go out and spray some more, or drive over in your UTV and take a closer look at that "weird spot" on the "back 80."
Farmers are very aware of the benefits of technology (why else would you spend half a million $ on a combine?) and will take it up if they see a benefit.
Re-reading the post, it seems that he and I might be talking about different things. I'm referring to farmers using remote controlled drones with cameras to check the state of their crops/fields without having to drive over hundreds of acres. That's an actual thing and is quite common.
OP seems to be talking about some kind of automated drone weeding (or just phrased what he meant poorly).
Very large scale, just not in the exact form GP is describing; instead, farmers drop stationary internet-connected sensors all over their fields, their sampling equipment GPS-tags results from every core sample, and tractors have computer-controlled equipment to feed location and quantity information to chemical dispensers.
I am not at all denying the benefits of technology, or that companies are working in it, but I am skeptical of how widespread it is right now. Therefore, I would want to see some numbers to verify such a claim.
