I thought there are robot harvesters guided by GPS already?

(Because people can't stand the thought of robots touching their food with their shiny metal robo-claws!)

Farming on private property is an entirely different scenario than having robot vehicles on public roads. I doubt he'd need anybody's approval to set things up that way.

It would also help if robots that could do the work actually existed.

In most scenarios where robots would be replacing human labor (especially in safety-critical areas like trucking), the engineering problems are a lot more tractable than the political ones.

GPS-guided farming seems like one of the simpler scenarios, and if finding labor is as difficult as the original post claims, one of the more likely ones, as well.