Both the Prius[1] and the Model 3[2] had similar software bugs related to their anti-lock brakes. Both companies had a software fix a few days after the bugs were discovered. Tesla's fix was pushed out immediately to every vehicle. Toyota couldn't push out a fix. They had to issue a recall and have a technician update the software whenever that car ended up being serviced. How many months or more likely years did it take for every Prius to be updated with the software? How many miles were driven in cars that were known to have faulty brake software because it was hard to update them? You have to consider situations like this when discuss banning remote updating.
[1] - https://www.networkworld.com/article/2245704/toyota-to-recal...
[2] - https://www.wired.com/story/tesla-model3-braking-software-up...
Isn't that exactly what we're doing? If someone pushes out a malicious change, do you know how long it would take for that change to propagate to the entire Toyota fleet?
It wouldn't.
This gives all the more incentive to get the software correct in the first place. The model of "get the software as bug-free as possible upfront using stringent processes, testing, formal methods, and not using software in the first place when it's not actually needed" is better than the model of "put software into as many components as possible to make it shiny and get the software good enough to release before our competitors and play whack-a-mole on the bugs later through updates". Instantaneous updates make it easier for an attacker to take control of the update infrastructure and push an update that will trigger a mass-crash of cars during rush hour. When people have to asynchronously take the car to dealerships over many months, it makes this attack harder to go undetected.
I think you've just identified the root cause of at least one set of problems. The essential control systems in a vehicle should ideally be separated from other vehicle functions to prevent interference, whether accidental or deliberate, from compromising vehicle safety. The approach now being taken by manufacturers with their always-online, increasingly automated cars may be undermining that separation, without necessarily having adequate safeguards in place to ensure safety and reliability are maintained.
Anyway, this is moot in most cars, as they don't have sold driving software anyway.
In this thread, I'm simply observing that there can't be a clear separation between control systems and information systems if we're going to achieve these kinds of autonomous functionality. We need a more nuanced solution.