That's a huge part of the problem, farming shouldn't be heavily mechanized in the way we do it. Monocrops, pesticides, fungicides, and huge feed lots all have terrible environmental costs. Even aside of Climate Change, soil erosion is a massive problem.
I used to be sympathetic to this line of argument, but I'm no longer so sure. Organic farming has lower yields, so to feed the same number of people, you'd have to bring more land under cultivation. That would presumably outweigh any environmental advantages you get from using less chemical pest control.
Second, the extra people you employ, aside from the obvious mind-numbing drudgery and hard labour you're ruining their lives with, would have a carbon cost.
Third, I can see that some pest-control chemicals are bad for the environment. However, it seems also clear that the demarcation line between eco and non-eco is not the same as the line between organic, and non-organic. In fact, it seems like there is no relation at all. There are many chemical pesticides that are not environmentally damaging, and many traditional farming techniques are environmentally damaging.
Actually if you look at no-till and permaculture it 100% can have the same or higher yields per acre. The process of farming also doesn't have to be mind-numbing in this case. The combination of AgTech/Robotics and no-till/permaculture could produce vastly larger yields vs Organic traditional farming.
That's for soil based farming, personally I think Hydroponics (raising plants in water with no soil), Aeroponics (Hydroponics but grown in vertical towers), and Aquaponics (closed ecosystem using fish to fertilize the water the plants are grown in) are the only real way to feed a growing population and not destroy the environment. The Netherlands is already the leading European exporter of food, here is a great youtube video that touches on some of the ideas. https://www.youtube.com/watch?v=5clOYWsNhhk
Bottom line is that traditional Organic farming isn't the answer anymore than modern factory farming. AgTech is something I'm passionate about and I honestly believe that if we don't adopt more modern science will we face a large crisis in our food systems sooner rather than later. Some crops will need to be soil based (grains and related crops mostly) but nearly everything else grows faster, more reliably, and with out the need for chemical treatments. There are a large number of Hydroponic and Aquaponic farms already in operation but the percentage is still very small.
Aside from the no-till/permaculture stuff (which has been around for decades now, and has never seemed to take off), what you are talking about is ultra-automated, extremely centralized farming - and in general, I kinda agree that it's a part of the future.
One issue is just that if you're trying to convert solar energy into calories, you naturally want to spread out over a large area (a field) then use an efficient process to do this (photosynthesis). You then want to make these calories easy to process with machines (monoculture), and to defend them against pests (sprayers), etc. So there are advantages for traditional farming that are rooted in simple physics and economics, and a lot of that won't go away.
I do think the use of robots to apply pesticides in a more targeted manner is probably something we'll see more and more of, but I think for most crops, building a super-controlled green house is probably never going to be economical.
Getting rid of those things would at most double the farm payrolls, which is still a tiny minority of Americans. For the most part, monocrops, pesticides, and fungicides have HUGE economic efficiency incentives ($ ROI / acre) even if you subtract the contribution to labor efficiency (humans / acre).
In fact, I expect most potatoes will not be touched by a single human hand until they reach the person who actually cooks and eats it.