Comment by mindslight

Documentation for hardware subassemblies produced by different manufacturers isn't getting conveyed through hallway conversations. Pure software can indeed be quite sloppy, but for vehicles we're talking about large scale cross-stakeholder projects where these things do get formally documented.

At any rate, for things a manufacturer doesn't consider important enough to document themselves then there can be a clear alternative requirement - release whatever upstream documentation they did use to create it, plus the software source code they developed on top of it. If it's not important enough to have been documented as its own product, then it also isn't a significant part of the value they're actually selling, right?