Yesterday, in traffic, I sat watching a woman attempt to park her car on the side of the road, one-handed, while having a conversation on her mobile, held to her ear with the other hand. Traffic was stopped, so I had a good opportunity to watch as she went back and forth, back and forth, never really making much progress.
It was only when she finished her conversation and directed all her attention to the task at hand, that she successfully got her vehicle parked. I felt bad for the cars in the lane she was blocking during the course of her attempt, but they also had a red light, so not much harm done, I suppose.
Sadly, the one-handed driver is a serious problem here. They don't even see you if to do so would involve turning their head. Don't even get me started on the ones checking their Facebook status in their laps. They think they're being subtle, but it's pretty obvious.