Your car, heater, air fryer, and lawn mower are consumer devices. If you modify them and they become unsafe, you're at fault.
However, farm equipment is classified as industrial equipment and if you can modify it to be unsafe without being an expert in that domain, then it is the manufacturers fault that you can do that.
Locking down industrial equipment so that it requires a trained technician to modify it is one of the ways that industrial equipment manufacturers try to mitigate the liability that they face.