Something I am trying to teach my children, with only small success - if you see a job needing to be done, just do it. My youngest wants to do chores to the very letter of the law - if you ask her to sweep the floor upstairs, she has no intention of sweeping the stairs - it's someone ELSE'S job. My oldest is similar, but part of it is his disability - he does what he believes is EXACTLY as you ask (this may be in part because when he does things on his own without mentioning it to us, it's often disastrous - we've discouraged him unwittingly, because he screws that up a lot).Because, a you said - they're grownups.
My middle one seems to "get it". Hence, she does her chores and responsibilities without being asked. Youngest doesn't want to do stuff like that - but to my SURPRISE, she will often do MY chores because I couldn't do them (had to leave for something, or got called away). But only yesterday, when I was putting dishes away, she said "that's (her sister) job - why are you doing it?". "Because she's at a friend's house and won't be back until this afternoon - and I am not waiting." She's getting the idea, slowly. She IS the only one of my kids who always does her homework on time, even though she's not the best student.