Particularly when the newer hires automatically assume if there is something unpleasant or even slightly outside their defined work, it's your job.
It is your job as their lead to make them understand "Somebody Else's Problem" is poisonous for their team (if that's how things are working in your team; when the organization gets large enough to make it worthwhile to have somebody else fix that problem, the same behaviour can be beneficial).
In my company (7 of us), every new hire gets an unassembled chair and an uninstalled computer and are expected to take care of it themselves on their first day (I guess you could say it's part of our company culture).