OK, let's just base it on what you have posted above:
$1.99 per shot
140 shots
Total $278.60
1 day shoot
5 days week
52 weeks a year
Grand Total of $72,436 per year
Sounds fair and straight forward, but:
I don't think you can complete all the shots in one day, so your logic of 1 day shoot is out
I don't think TS is offering the same number of shots @ $2/- everyday nor is there so many 140 shots @ $2/-each to shoot everyday, so your logic of 5 days a week is out
I don't think you can base it on 52 weeks since you can'r even fill up 1 week, so your logic of 52 weeks a year is out
Since there is no 140 shots @ $2/shot everyday, no 5 days a week of $278.60/day and no 52 weeks of fully book shoots everyday, so your logic of $72,436/year is also out.
Seems logical to you?
And we have not even touch on post production, overhead cost, marketing to get 140 shots at $2/- everyday, etc .........
Yes you are right, it is not an ideal world, people makes it complicated, especially when they simplify it too thinly, so what do we do? We explain, we share from personal experience and we try to manage it.
You could be right but it doesn't mean it is impossible. Perhaps I am too immersed in the R&D environment - make things out of the nearly impossible.
Education is always good especially from experience. The importance I guess is to stop short when it comes to decision.