How would the person know that someone was not going to be coming right then to pick her up. The person would then be caught
Well, people who commit crimes take risks, big, big risks. Sometimes they're lucky, sometimes they do get caught immediately.
Seriously, look at crimes of this sort. Ask yourself what would have happened if someone else had turned the corner, driven down the street at the right time.
One example that comes to mind is the man who killed Sierah Joughlin. In the past, he had tried to abduct someone, she fought back, and a passing motorcyclist rescued her.