Who is going to look at that stuff apart from technicians? Most users have no clue how the functionality of their vehicle is achieved and they don't care.

For argument's sake, let's assume there is a userbase for this type of information. It would be possible to show diagnostic information like DTC or run DID routines from the dashboard but this is already possible from any cheap offboard tester, via a phone app or laptop.

The reality is that even if an OEM wanted to provide detailed diagnostic information, they don't know it either because the information isn't disclosed by their supply chain. Companies such as Bosch, who supply brake ECU, are extremely tight lipped about their intellectual property. When something goes wrong we use a special development version of the ECU to record the associated software variables during the fault and present that as evidence but we don't have access to the source code.

Modern products are not designed to be repaired. They want us to continually buy new shit. Basically anything with software in it is an absolute nightmare to maintain. It makes me depressed just thinking about what a clusterfuck this landscape is.

Source: control system engineer for a large OEM.