I agree with this. But it's worse with a cell phone, because the person on the other end is completely unaware of the situation that the driver is in. If I'm talking to someone that is in the car in rush hour traffic on the freeway, and I need to merge into a packed lane, the other person in the car sees that situation and generally the conversation is automatically paused until I'm done changing lanes (unless it's the kids, then I just ignore them for a few seconds). But on a cell phone, the person on the other end is going to keep talking expecting me to listen, and I'll feel obligated to continue the conversation when it would be better to put it on pause. There are lots of situations like this - turning left through traffic, avoiding debris in the road, etc..