In addition to cost and labor savings, yield increases play a big factor in getting ROI from your spraying drone. The short answer are these two things, and there are a few other reasons but we'll start here.
1) drones aren't stopped by ground conditions so you can still spray when the ground is wet without getting stuck or causing soil compaction. Not having to contend with weather + the ease and quickness of drone applications allow you to get crop protection products out more often providing optimal protection as part of your IPM. Healthier crops = better yields.
3) Removing tramline (tractor or vehicle tire) losses means you won't be causing fruit drop or running over your crops. Apply fungicides, miticides, etc., as often as you need without having to gamble with nature or damaging your crop.
Learn about and calculate your yield increases with our free calculator HERE