Well, yeah. Where have you been? Everyone does that now, even Millennials. I'm surprised she even has a hand on the wheel and that both legs (as far as I know, anyway) are still on the floor.

How is it not that everytime someone does that they are instantly convicted of dangerous driving as they have just recorded proof of the crime and made it public?

This would usually be a traffic infraction. Depending on state law, it can be hard to issue infractions that did not occur in the presence of an officer. One could refer it to a prosecutor and they could issue an infraction. You'd need someone's real name, the jurisdiction it occurred in, and when and where it occurred. You'd also need pretty clear video evidence. Prosecutors are usually very overworked, often with more serious criminal cases. A state trooper could also just drive around and write this or similar tickets all day.

Sort answer: it'd be a big headache and the criminal justice system usually has better things to do. If it got super high profile they might.

Also, obviously, you'd need someone to see it, find out where it happened, and refer it to the relevant agency. Which is unlikely.

Also she is in the back seat here.