That's fair. A builder could build a terrible house from the same blueprints as another built a great house.

However that's not really what I'm talking about. Assuming some minimum level of quality, 2 houses built from the same blueprints with the same materials and finishes, in similar locations, and by similarly skilled craftsman will be pretty much indistinguishable from each other to the end user.

That's not the case with software.