This would require a very good image recognition software! Anyway yeah I do agree that agricultural robots are quite interesting and profitable at least in the near future.
With half decent radios, the brains of the bot could be stashed back at HQ, which would really improve the amount of computation available.
The physical manipulation part would take some work for sure, and the robot itself would be fairly expensive to make, but it's all pretty achievable. You need it to do more than a BobCat while costing less.
It's not "Uber for $sector" but it can be done.