system
A chat on subreddit /r/wallstreetbets
human
That's not exactly accurate though.  There isn't really anything in equipment or even cars for that matter that is  top secret and proprietary. The system for cars has been more or less open for at least 20 years. In fact most cars today you can edit and add and remove many different software features that you didn't originally pay for like cruise control, drive modes, or even some of the more luxury tier things like driver assistance etc. All the while maintaining core functionality. Even cell phone codes are open source anymore. 

Deere just wanted to pull a xerox or McDonald's ice cream machine situation and corner the market on repairs. City BS examples like safety and emissions nonsense. Deere service was raking in the money charging huge service call fees, I mean I used to get charged out at $100 an hour almost 20 years ago.
gpt
The emissions has been the biggest issue. If the tractor senses something is missing or wrong, it goes into safety mode and is unusable until repaired. This is a very costly service call, and farmers have been suing John Deere for access to their machines.