Earlier quoted context omitted.
The number of times that "you can't stop / brake / slow because someone behind you will run into you" comes up in these threads is always alarmingly high.
Indeed, it reminds of this article, which thankfully didn't end up killing anyone: https://www.wired.com/2015/07/hackers-remotely-kill-jeep-hig...
Are there seriously cars on the road with complete fly-by-wire brakes which have no pure mechanical backup? That's horrifying. How did we go from dual redundant hydraulic systems that work (if in a reduced capacity) even when the ignition is off, to something at the mercy of some code that can be bamboozled over 3G?