You can't compare a multi-family house and a single-family house.
However, I would see a comparison obstacle more in the apartment size than in the usage: in smaller apartments, hardly any reducible expenses for kitchens and bathrooms are spread over less space. What is spent more on stair width, fire protection, and impact sound insulation in the multi-family house is roughly regained with aluminum just for the front door, and for the windows, one settles for plastic again.
But in principle, I agree with you that reference values should not be transferred between building types.