As I've said before, I think it would help if they put a less commanding voice on them. But it's still down to the idiots who listen to their sat nav rather than looking at the road in front of them and deciding whether it's suitable or not.
I'm obviously very odd as well. I set my MP3 player up before I drive off and then refuse to do anything more than maybe press the "skip track" button. I wouldn't even try to pick songs and drive at the same time.