In addition to all the legal restrictions on "reverse engineering" (i.e. examining how stuff works) and circumventing DRM, as technology advances, using technical means to restrict otherwise legal end-user activities is becoming a big problem.
That you're legally allowed to repair your tractor doesn't help much if the on-board secure TPM chip flags your replacement parts as counterfeit, locks the engine, and reports you to the manufacturer so they refuse to sell you parts in the future.
This is something I've wondered about. For cars there is a bunch of regulatory stuff that might preven you from doing this, but I believe the regulatory burden on tractors is much less. Why has no one just built a full on control system swap for tractors? Yeah, the OEM control board won't recognize your replacement part. Or it won't tell you whats actually wrong. Etc. Etc. But if you just replace it with an entirely OSS control system, that problem goes away.
I know that this probably not a trivial task, but, given the amount of money at stake, it feels worthwhile, but maybe I'm just underestimating the degree of integration of the current control system into the parts. If everything down the internal engine sensors is running priprietary, encrypted software and you basically have to tear it down and replace every single electronic component on the tractor, then yeah it probably won't ever make sense.
The software is the value proposition of modern equipment. Making a tractor is comparatively easy - we've been making them since the age of steam. Making a tractor with all the features of a day cab tractor truck, plus EPA compliant engine management through a host of proprietary systems, plus the systems and sensors needed for self-driving... Very non-trivial to replace.
That sounds like a fun project if you are a bitcoin millionaire that moved to a ranch. Rip the components out and try to re-engineer all of the control systems.
Given the number of sensors, it could also be a great way to collect open data for farming innovation, environmental data, etc.
That you're legally allowed to repair your tractor doesn't help much if the on-board secure TPM chip flags your replacement parts as counterfeit, locks the engine, and reports you to the manufacturer so they refuse to sell you parts in the future.