I have watched people drift out of their lane and run lights and so on while holding that phone against their head. I have had to honk at them while slamming on the brakes because they decided to pull into my lane without looking to see if I was already there. I have wished that someone would take that damn phone away from them so they could drive without crashing into me!
I have had to do this to people who weren't holding phones to their head... more times than I care to count... it happens whether people talk on a phone or not.
It's even worse when on my motorcycle.
If a driver isn't paying attention anyway, it doesn't matter if they are talking on the phone or not.
The nice thing about standards is that there are so many of them to choose from. -- Andrew S. Tanenbaum