According to existing product liability law (if I'm reading this correctly, I am not a lawyer), if John Deer allows a farmer to insert an SD card with different firmware or settings or whatever, John Deer is still liable for the tractor even if it was changes that were made by the developer.

If that 3rd party firmware overapplied fertilizer - JD would be liable. If the auto driving feature was modified and ran out into the road and killed someone, JD would be liable.

Product liability for industrial equipment falls in different category than other product liabilities and all industrial equipment (including tractors) are classified as "unreasonably dangerous" and it is the responsibility of the manufacturer to prevent 3rd party modifications that may result in damages that could have been foreseen with the existing setup.

If John Deer allows someone to change the software, then it is foreseeable that anything that is software controlled may be changed and behave in a way that is unintended... and John Deer is liable unless they prevent that software change.

> all industrial equipment (including tractors) are classified as "unreasonably dangerous" and it is the responsibility of the manufacturer to prevent 3rd party modifications that may result in damages that could have been foreseen with the existing setup.

This is not necessary. We can choose to not do this. Also "could have been foreseen" carries a lot of water here. These products shouldn't be unsafe to make minor repairs on any more than they should be unsafe to operate.

The Brush Hog case that I mentioned elsewhere had a protective plate removed (it was apparently commonly removed by farmers) and attached to an older tractor. When the operator (not the owner who made the change) was mutilated from the mower, Brush Hog was liable because it wasn't harder to remove that safety plate.