About 3 years ago there was an item on the news. The vehicle involved was a new Jeep Cherokee (which was the same year as mine). There was a security hole in the UConnect computer system that allowed hackers to access all the computers in the car, lock out the driver and take complete (braking, steering, acceleration, radio, HVAC, etc.) control of the car. There was a recall for my car and a security patch was installed.
The thing is, hackers tend to be really, really smart people. As I understand it there is no such thing as an unhackable computer (unless it’s air-gapped - not connected to the internet in any way). I know my Jeep and my neighbor’s F150 (and probably every other new car now) receive over-the-air computer updates, even when the vehicle is not running. So it’s only a matter of time before someone decides to take over someone’s Tesla and do something really bad. Computers do a lot of good things in modern cars (maximizing fuel economy, for example) but self driving cars strike me as a bad idea, not only from the standpoint of idiots that think any kind of driving is set and forget, but also from the standpoint of people with bad intentions accessing the car (think rush hour on a major freeway and a hacker taking control of an 18-wheeler loaded with gasoline or propane, or…?).