I literally see this happen almost every time I'm at a stop light. Someone in the queue is looking at their phone and by the time they react only a handful of cars have gotten through a light that's normally timed to move them all. Multiply this by hundreds of intersections and the effect leads to rising travel times and frustration across the board. I've also noticed a large uptick in people running stale yellow lights/newly red lights, I believe this behavior is precipitated by the red light texting crowd.