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).
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.