No one is forcing the car dealer to make public these numbers; & frankly, they are made up numbers, anyway. It is part of the marketing plan to allow buyers to “believe” they are paying not much over cost, when actually, the dealer is making a nice profit.
Just because the dealer tells you his “cost” doesn’t make it the truth.
I agree with you on that - but I’m a bit taken aback by the whole notion that a customer should negotiate based on the profit the business makes. To me, that’s simply not relevant.