And you never finish gathering food. As soon as you do, you eat it and you need more.

You can certainly finish gathering food for the day/week/month/season. Knowing that you're gathing at X bushels per time period and you need Y bushels to finish out the season, it's pretty easy to figure out when work is over for the day, even if there is "technically" more to do (there's always more to do everywhere in every business that isn't bankrupt and closed, that doesn't mean every hour of every employees day requires more contributions of labor)

There was no food preservation though.

There was all manner of food preservation. Smoke it, salt it, pickle it, ferment it, dry it, thresh it and bag it up in cold storage.

There's nothing special about software. There are tons of finished software projects, many of which I worked on. There are probably more finished software projects out there than projects currently under development.

"Almost any work in history had and 'end', i.e. you could finish it."

I'm unsuccessfully trying to think of any examples. Fine arts painting, maybe?

"gather eggs from the chickens"?

Oh, you'll get another batch in almost exactly one day. There's lots of mythology about the chicken cycle (as if theres only one "chicken") being 25 or 27 hours vs our wall time clock, and chickens don't live forever, but...

Same line of thinking WRT military, farming, etc.

On a very small scale I'll never type that specific line of code again, probably.

There are very few ways to earn a living that don't terminate the procedure with "repeat from beginning of procedure"

No, that's not what we're talking about. You gather eggs until there are no more eggs in the coop. That task has an end, and then you are finished. You may begin a similar task again at a later period.

If you were asking about a job where you do it once and it stays done permanently forever, that's silly, and it's not what the guy you replied to was referring to.

PhD research?