I don't think anyone was claiming it doesn't apply to pretty much any job. (In the original context, the point was that it does apply to pretty much any job, and to a host of other things besides.)

It will apply better to some jobs than others. It needs

• the people doing that job to form a community in which social status is actually meaningful
• mere membership of the community to be seen by its members as conferring status
• doing the job effectively to lead to promotion to a position in which one can do it better
• (preferably) status within that community to have some currency elsewhere.

Those are all true for academia. There is definitely such a thing as the academic community, its members relate to one another socially as well as professionally, academics tend to think highly of themselves as a group, promotion means better opportunities for furthering academic research (oneself or by organizing subordinates and taking some credit for their work), and -- at least in the nice middle-class circles in which academics tend to move -- there's some broader cachet to being, say, a professor.

I think they're less true for ditch-digging. So far as I know, there isn't the same sort of widely-spread confraternity of ditch-diggers that there is of academics. I've not heard that ditch-diggers see themselves as having higher status than non-ditch-diggers. I think a lot of ditch-diggers are casual labourers with no real prospects of promotion, though I confess I don't exactly have my finger on the pulse of ditch-digging career progression. And there are few social circles in which introducing yourself as a ditch-digger will make people look up to you.

So yeah, this structure applies to things other than academia, but it does seem like it applies better to academia than to the other example you offered.