Take the following as truth: Postal Service may differ greatly from other postal systems in labor cost, automation, route topography, worksharing, mix of mail by shape, and the percentage of non-delivered mail, etc., we cannot expect the cost estimates furnished by the model to be extremely accurate estimates of particular non-U.S. systems.
Then the following statement: "Postal systems in different locations face different conditions which may require different cost models." is true, false, or inconclusive?