A more innocuous example of diffusion of responsibility can be seen when you compare public and private spaces. To wit: at my university's library, at any given time, at least five computers are down in the lab. The computer lab serves upwards of a few thousand students a day, and it's never empty. However, these computers are still down, when the help desk is not more than ten feet away and the university's own private Geek Squad is right down the hall.
Basically, it goes like this: you notice a broken computer and move on to the next. Diffusion of responsibility compels you not to inform the staff. "Surely, someone else has already reported this," you rationalize. But the computers are still down, and no one seems to mind much. There's always other computers, and someone else will get around eventually to reporting the broken computers.
Whereas, at home, if your computer breaks down, you take action immediately. What's the difference? At home, you have no one to turn to, and the action lays firmly in your own hands. You have sole responsibility. At the library, the staff has the responsibility to maintain their equipment, and the responsibility to report malfunctioning computers is dispersed through the thousand of patrons that the computer lab serves daily. Kitty Genovese, but it's the same phenomenon.
See also: littering in public places, restaurant menus with spelling errors and, if I may dare to speak out so, the state of the world. No one feels the need to personally take responsibility for the thousand and one problems, great and small, that we encounter on a daily basis. Someone else will always do it. Someone else will always bail you out.
Fight your own battle against diffusion of responsibility in whatever way you feel you can. Just don't assume someone else will do it.