There are precision farming systems that (according to their marketing materials) will allow you to precisely spray fertiliser only at plants, and weedkiller only at weeds. This saves money on chemicals, and helps the environment through reduced run-off.

Of course, adoption isn't universal [1] - a large farm will see a much faster payback time for the same bit of equipment, for example. And many farms will have other priorities for their limited capital; tractor auto-steer is much more popular than precision weed control.

[1] https://core.ac.uk/download/pdf/147418633.pdf