People aren’t buying them for price, but the first sentence discusses it as if it’s relevant.
My assumption are farmers are trying to skirt the eco rules for vehicles in some way. Which by the way is insanely annoying and has caused issues for all the farmers I know at one point or another. Worse, you can’t fix the ecosystems on your own so you have to get them serviced costing quite a bit and importantly putting your tractor out of commission for a while. It’s why older tractors have a premium