I dont find the example flawed, both sides you've got people saying "Well just be careful!" or "Just don't drop it/crash your bike".
Both of these things are often unavoidable at the moment it happens, there have been times where I've been holding my phone and texting on it, I'm not carrying anything else, I'm not walking, I'm just standing still and texting, and I have suddenly lost my grip on the phone. Also what if someone bumps into me and I drop my phone? That has happened to me before.
Exactly. Or if you're carrying a bunch of other stuff with the phone, and you lose grip on some of it, and the phone goes flying.