You underestimate the ability of modern unmanned flight controller, There are already companies specializing in converting manned aircraft to unmanned. There is even a company supplying kits so you can convert your own aircraft to unmanned.
It's already happening in real life and the flight controller does all the heavy lifting so the pilot only has basic controls to concern themselves with. A vast majority of drone tasks can be done autonomously. Your typical drone ag pilot does all his work before hitting the take off button, including a survey flight of the area with a suitable drone. Then he just monitors the telemetry to make sure he got all the preflight programming right. Flying manually is far to inaccurate compared to autonomous flight
Drones are not the only answer but they make sense for some applications.
You massively over estimate the requirements to be a drone pilot, I train heaps of them and they are not that qualified. The current RePL syllabus is based heavily on the PPL syllabus.
That said, these days a drone license is treated more as another accreditation, like a fork lift license. Most of the people I train are surveyors, agronomists, farmers, engineers, geologists, emergency services, educators etc. The drone license is something they need to use a tool that simplifies their job or makes it easier and more accurate to gather data. Typical wages for a basic drone pilot are in the $35-$45/hr range.
As for the spraying side, that is a whole separate issue with different chemical licenses and standards for each state. I believe the AAAA is working on an unmanned version of their SpraySafe accreditation at the moment. There are plenty of operators offering broadacre spraying services, often using swarms of 3-5 drones per operator. Google will show you heaps of them.
Personally I can't ever see drones replacing all flying industry tasks, the current push apart from military applications seems to be ag and unmanned freight.
It will be very interesting to see what happens with the UTM (Uncrewed Traffic Management) and airspace changes that Airservices has been working on.