>>4094052Because it's the most boring of the props, it doesn't say anything about the subject, doesn't put into the viewer any insight on who the model is.
We can associate a camera with something, a cigarette with being "serious" or dark or having a break after a long drive, a map to someone on a road trip in a vintage kinda way, hell even a colourful sneaker can say more about the person than a phone.
A phone says literally nothing, everyone has one, they all look the same, it's unfitting, nothing is shown on the phone, she could be looking at the camera, looking at something notable on her car, instead she's probably checking Instagram?