Pick the worse situation: a documentary filmmaker keeps the camera rolling as a teenage girl is beaten by her father; a documentary filmmaker intervenes in the above situation, befriends the girl, pays her a cut of the film's profits and ultimately helps her get a job or into college. There are many other possibilities found in the spectrum of doc ethics that fall between these two extremes, but I think every non-fiction film fan should have a basic preference for one or the other. Either you're someone who thinks docs should be primarily objective and not interfere at any point (save for life-threatening violence) or you're someone who thinks documentarians should be life savers whenever possible.
I got in a debate recently with someone who thinks the former situation (seen in 'Last Train Home') is totally unethical. She thinks most people agree with her on that as well as her belief that documentary filmmakers should become more involved with their subjects and provide for their welfare if necessary and doable. Maybe you are one of those people who think this is true. I've often written about my dislike for 'Born Into Brothels,' with its onscreen fundraising that seems more self-serving than selfless charity, and I just as much hate the mere charity aspect of the film. Filmmakers can reveal and even advocate, but they shouldn't attempt to do the rescuing themselves.