^Flying cars are a very bad idea unless they're computer-controlled. People have enough traffic accidents in two dimensions. And if a normal car breaks down, you can just pull over to the side of the road, rather than falling to a grisly death.
I totally agree. I couldn't sleep at night without the thought that one of them might come crashing out of the sky into my house.
It would be a terrorist's wet dream if they ever became a reality.
However this is Star Trek where people are generally good people..on Earth at least. Only have to worry about someone warping a ship into the planet....