I think it's one of those situations where she was between a rock and a hard place, potentially.
Maybe her phone was dead. He was driving at 60mph and weaving over the road - she must've been traumatised and terrified too. He might've even lied and said there was nothing there (when he checked)
Without knowing the ins and outs it's hard to tar this woman as culpable. Personally I'm open minded enough to consider that she is likely traumatised too.
Had she been seen on CCTV laughing and smoking a cigarette... I'd feel differently.