That would be quite shocking. Links?
Fast forward to today: getting access to the canbus (e.g. via headlights) allow you to steal the car: https://www.theregister.com/security/2023/04/06/how-thieves-...
Given the integration of these modules, is it that weird that you could send signals the other way?
No, but there are simple solutions to this: a firewall, which is how this has been fixed on some cars.
You trust state actors to not force them to not get it right?
Why would it be shocking?
It would be shocking if it weren't possible. Being a car does not confer any sort of magical protection against hacking because "it's just a car" or something.