Do you have some examples where the government made these returns?
There are other reasons, some good, for doing so. Amtrak, for example, might better have been formed as a nationally operated part of the transit network rather than as a quasi-private-sector corporation that is neither fish nor fowl and suffers for it. Municipal utilities often work quite well at least here in Northern California, though at the national level I only know of the TVA and the western dam systems.
Someone was, the simple word you looking for is corruption. The end goal of a corrupt state might be to build a road, but the specific cash flow ending up in well connected hands has absolutely nothing to do with the stated goal.