Correct me if I'm wrong, but when we are driving, we are obligated to obey the rules of the road. That being the case, we have every reason to believe that everyone else is obeying the rules as well. Good driving practices include being alert and anticipating the traffic around us. To what extent that is possible, I can' say. 
So, when driving down the freeway, it is reasonable to expect traffic in the traffic lanes to travel at the speed of other traffic. Maybe a deer jumps out or some other event causes someone to hit the brakes. Hopefully there is enough distance to stop, or there isn't a car in the next lane that would be hit if one swerves. We don't know why the woman stopped in a lane of traffic on the freeway, or if  Nytasha had eyes forward. I'll bet that Nytasha didn't expect the car in front of her on the freeway to stop. No one does.