I've worked at Deere as a contractor. Not on the tractor software as I didn't have access, but I would put most of what I saw as towing the line of over engineered.
There were certainly parts that were exceptionally easy to work with. Many, many, many repos all over the place doing various different things and inside of some of those you would find some very cleanly written code with excellent tests, examples, and documentation. The problem was once those nice little libraries, tools, etc got brought together it became a mess.
