Embedded insecurity
It's the Automotive Sector. It's all done to a price and a template. Of course you could update it, except only at a dealer and for a large fee.
Think of it as a large phone that doesn't get any support.
The exception would appear to "Muskmobiles" which get updates, some of which may not be quite bug free. We're all used to ignoring the built in SatNav that is well out of date and can't find anywhere built in the last 5 years.