I gotta say, in that case the cop looked like a complete douche bag. However I do know from experience that the moment you leave your car that cops fucking flip their lid and turn into insta-pricks because I guess they take it as threatening them. It's kind of like this unspoken rule until you learn about it yourself (at least, thats what I think). So that was the major thing she did wrong there. Still, he didn't have to pull her out of the car and treat her like an animal in front of her kids and then leave them in the car for 40 minutes on the side of the road until someone picked them up.
In case anyone is curious, the way I found out about the step out of the car rule was when I was in high school. A buddy of mine lived on a strange little street that was always packed. He had a bunch of people over one night and there was no where to park, but across the street was an old unused parking lot (which is now The Dump for anyone in the area). When I went to my car that night, a cop spotted me and pulled up behind me. I didn't even have the key in the engine, so I figured I'd save the cop time and get out and tell him why I was there. Well, the moment I stepped out of the car the dude turned into this enormous prick and starting shouting "GET BACK IN THE CAR NOW!" like three times. So once I get back into the car, he comes over and says "What are you doing out here?" like an asshole. I told him the deal and said "Listen, I didn't think I was doing harm getting out of the car. I figured since I Just got into it I'd tell you what was going on." and that's when he told me to never leave my car when a cop pulls you over because they automatically go on the defense, and then told me to never park there again. Asshole.