C172 and similar assisted the horses in a muster, as did the motorbike - the "expensive" R22 has essentially replaced the horses.
Chemical companies produced a product to suit aircraft spaying - they can concentrate and adapt to suit lower,slower selective drone spaying.
Drones will be used when the agricultural data can see the benefit in $ terms. Not only are our framers pretty tough, they are pretty well educated. (Many do "research" far from CAsA eyes).