I don't see how this would help, because the default behaviour in a computer software is to inform the user that an error occured, please press enter to continu

I don't see how this would help, because the default behaviour in a computer software is to inform the user that an error occured, please press enter to continue. When you write software for a car, you always have to think about the impact of your code in the car, and pressing enter or crashing the sw is not the safe way to respond. So if the comms fails, you have to ask yourself what should the thing you're writing do and what the driver would see or think. The problem with this architecture is that when you have a physical sensor, it is obvious when it fails and you can easily add contingencies. When you have a sensor other CAN or whatever, you are adding new failure modes: sensor OK but communication not reliable, or sensor info not yet received. You thus need more code to handle those new failure modes which are tricky for the average sw guy.