FWIW in this thread, I'm a Navistar Defense Master Field Service Representative. (Navistar Defense qualification is identical to Navistar proper)
We were issued full-stack military PCs with diagnostic software for every wheeled vehicle the military owned at the time. (2007-2010) HOWEVER only the International/Navistar software was unlocked on our PCs. The military was issued a service package with every new vehicle which had *all* of the software unlocked; of course, nobody knew how to use it and for them to take full advantage of the diagnostics, they needed someone like me from each relevant company to teach them (Navistar, Allison, OshKosh, BAE etc.) so I had a few years to sort through the specifics and politics of it; at the end of the day, it has *NOTHING* to do with warranty, or safety, or data security. It has *EVERYTHING* to do with licensing revenue.
Simple As.