So considering only car constructors employees is a pretty inaccurate estimation of man-hours/item in that scenario.
EDIT: comma <=> satan
Perhaps if some of the larger manufactures have in house teams for things others outsource, it will be largely insignificant given their larger size.
Essentially it's not significant.
For example, concerning the subject we are discussing in the first place, Tesla because of the specificity of their cars probably have to produce themselves a huge part of the components of the car whereas Ford, Volkswagen,... are now to a point where a huge amount of the parts of their car are similar and can be outsourced to contractors that will decrease costs by producing only one type of components in huge quantity and provides to multiple constructors (who looks more and more like assemblers nowadays).
So I agree that it is in fact not easy to compare manufacturers on this metrics but I would believe that it's actually suggesting that Tesla does a lot more in-house than conventional car manufacturers.
Not sure but we might be having an apples-to-oranges comparison here:
If man hours pr item are significantly better for one but the other has much lower materials cost pr item (motors, sales etc) or enormously lower fixed costs then it is not so easy to say anymore.
It's a very important metric. The number of man-hours per item is a good stand-in for production costs. It isn't perfect, materials are outside the math here, but it works.
I'm interested to hear of how much staff time is put to new production/development and how much is dedicated to maintaining the current fleet. I have to believe that Toyota walks away in that area too.