Just wondering

I read something the other day about how many people died this year while driving and texting. I just wondered how this was determined. What is the evidence? Is a phone found in the hand? Did authorities at the scene pick up the phone and find a text that was mid-sentence? It seems it would be hard to prove such a thing unless there was an eye-witness or someone on the receiving side of the message who could associate the time of a wreck with the time of the correspondence. I would think that when a wreck occurs, the phone goes flying. I'm not trying to make little of texting and driving, it's just that people are too quick to jump on a showboat, requiring no evidence in taking up a new mantra.