I think it's just natural human curiosity... And really I think would prefer crawling by in slow traffic than cars whizzing past and not even realizing there was a situation ahead which they needed to slow down for.
I'm not sure about trying to distract kids from it..guess it would depend how serious the accident was, but especially for older children it presents a good opportunity to discuss road/driver safety. DF is a tow truck driver, so I guess DD will be somewhat used to growing up 'around' the debris of accidents.