Today you, tomorrow me 
This actually makes much more sense than a rich family stopping. I think its got to do with our psychology. We support each other because one day we'll need the support ourselves.<p>The richer folk see less need in stopping to help because they feel like they're self sufficient; in other words, if they themselves run into car in the future, AAA and cash will bail them out.<p>This more humble family however knew that if something like this occurred to them, they would definitely appreciate the help. Thus they were more inclined to stop. So I don't know why people here were so surprised...<p>Hell, the guy himself states all I just said in four simple words. Still, it was quite a touching story.