Most people refuse to help as they don't want to get involved. look at when motorcyclists come off, I've seen people start beeping because he is taking too long to get up and get traffic flowing regardless if he has come off on his own accord or other reasons and may have broken a bone(s) or any other serious injuries. What about when fights or muggings occur in broad daylight with witnesses, its very rare for people to get involved. Even when police put signs out requesting for witnesses most people who are key witnesses do not come forward, in some cases not any witnesses Same when cars break down etc...
So its no real surprise, people see no need to get involved and usually have an excuse, like "that person should of had break down cover" or "if he was getting mugged he should of called the police", when really ringing the police could of ended up with muggers seriously hurting the subject in question.
Then you get people who are worried of getting hurt, look a few months back to inner London crown court, a man got stabbed just before he entered the court doors by a big group due to being a witness against the gang or a group of a few members.
Then you get the other public opinion of why bother? That person won't get anything. I was attacked randomly once, stood my ground, got the persons details from his vehicle and suffered permanent nerve damage in my hand, you could tell he was also well over the limit, ontop of this he claimed to be a police officer. Police traced him down 4days later as he was using a friend's/relative's car, the drink driving they couldn't proove, they refused to come out on the time of the incident as they did not see it being urgent. By the time they found him they had no evidence of drink charges, followed by all they could do was make an arrest, issue a warning and force him to write the most lamest unsympathetic letter addressed to me.
So no surprise. But when you get caught of doing 32 in a 30 zone and end up with 3points and a fine because the police wanted to enforce the limit your blood boils as you have always been a good law abiding citizen when all the above happens, imagine what kind of public opinion people end up with?