How? There are dozens of closed source microcontrollers and one big central unit involved in making this happen. Surely any decent tech company has the ability

How? There are dozens of closed source microcontrollers and one big central unit involved in making this happen. Surely any decent tech company has the ability to safeguard their components against tampering like that. "Right to repair" doesn't give you access to the source code, devkit and flashing hardware. And do you really want to mess with a central component of your drive by wire system?