...is that people like this don't realize the implications of technology on his 'fantasy' of how things could be.
I don't want my autonomous car talking to ANYTHING that I don't control/manage/filter. I don't care what some unknown car reported, I don't trust that car. I'm no member of the tinfoil hat brigade, but I do work in software security and I assure you - IT IS INSANE to presume that ANY automaker is going to produce software that isn't trivially easy to pwn in the next decade. They all roll their own solutions (or have someone produce a custom solution) and using cryptography as an example - don't roll your own, even if you *really* know what you're doing, you're likely to regret it.