Earlier quoted context omitted.
People make this argument a lot, but the main counterpoint is that if you sell faulty brakes, it's hard for someone externally to exploit that on a massive scale. If you sell faulty car software, it's easy for someone to exploit that remotely on a massive scale.
How exactly does blocking car owners from working on their cars stop someone from exploiting them on a massive scale?
With sofware, it is as simple as pushing a faulty OTA update. A large portion of all the cars will _instantly_ be impacted.