In this case, it was more of a legal issue that the Good Samaritan did which no-one actually knew at the time. Because he moved the old lady away from the accident and attended to the old lady's needs and cleared some debris away (presumably) he has already interfered with the accident site before the police came to sort everything out.
In China, if there were two car accidents, everything must be kept as it is until the police arrive to ascertain who was at fault and then decide there and then what should happen. As I understand it. It is a way of allowing the policeman to see exactly what happened and not rely on eyewitnesses accounts.... it is just a different way of doing the same job here when the police gets called to a serious injury car accident.
However, this court case that the old lady had against the good samaritan was the following: "Why would he pick me up if he didn't create the accident in the first place? He must have picked me up because he has caused the accident in the first place!"
During the court case, the legal issue of removing someone from the accident site to attend to their wounds/injuries was brought to light. So this was why there is confusion over this thorny problem of attending to injuries at an accident site.