The problem of remote control of a car is that you cannot assume it'll happen for good reasons, or by the people that you think. It's the same issue of having an encryption backdoor, theoretically held by "the good guys"
If a vehicle can be controlled remotely, it's because there is some authentication mechanism that allows that to happen. Anyone that steals the keys can remotely control the car. Imagine how much fun kidnapping becomes when you can do it from the comfort of your own home.
Same problem when people talk about blockchain-based DNS. If the only thing protecting something is a digital key, then you have two problems: Making sure the key is not lost, and making sure nobody copies it. Stealing keys becomes more profitable than ever, as there is no more recourse: whatever you were protecting is compromised.
So the question is: Would it be a good idea to let a terrorist or a gang control everyone's car? Because that's the door you are opening the second you let police do it.