…don’t exist everywhere.
Sure, it would be great if every opportunity and project came with the resources and clarity of purpose to make roles and responsibilities clear, but the reality is that these are often a luxury afforded by established businesses.
And even then, said titles are often given as a formality rather than out of necessity. Executives and founders and self-starters don’t have clear delineations between what they do and what their counterparts (or employees or secretaries…) do; their job is to get it done, whatever “it” is, and no matter what it takes.
There’s a marked difference between the person who says “that’s not my job” and the person who doesn’t say anything at all (because what needs to be done is simply done, and there’s no discussion needed).