An example for assumed responsibility would be this guy I know who develops his own software for a living - they lengths he goes to circumvent the glitches of the operating systems are impressive. For example even if the java installations on the client machine are completely effed his software will still try to figure out the best match for his needs and will 'just work' - Although he could just lay back and take a position of "Well, if the user can't correctly install java it's his problem" he doesn't. He feels not only responsible for implementing his software. He feels responsible for the users experience with his software. (And given the fact that he is able to make a living from a $30 software package his commitment seems to pay off)
It's unrealistic to expect this kind of behavior from people who are assigned responsibilities - especially if they don't believe in the goals or the underlying beliefs of the people who try to assign the responsibilities.