Its not a matter of union or non-union labor, but rather how the project is financed. If the construction is financed with federal funds, the Davis-Bacon law comes into effect and the workers must be paid the �prevailing wage.� Most states have a �little� Davis-Bacon law with the same requirement for state funded projects. Any decrease in construction costs would be mostly attributable to a private vendor�s ability to construct the facility faster -- thereby incurring less interests on the $ used to finance the project. There are, however, costs that are not considered in the public/private comparisons. For instance, the depreciation expense write-off that the private sector gets. In other words, taxpayers all over the country subsidize the private construction.