I do aggree with you to some extent here. I think that private corporations (with very few exceptions) by their nature do not have the wellfare of the other citizens in mind, but to maximize profit. The two are in most cases mutually exclusive.It could be a double edged sword we could use to reduce the government. Government justifies it existence by providing services that could not be provided by private industry. I.e it would be too cumbersome to charge for road use if all the city streets were private with owner changing every cross section. Imagine all the fee collection check points... It is cheaper and better solution to collect taxes so the government builds and maintains roads.. until you can have a GPS device that can track and collect fees for road usage.
That said, nobody prevents the government from using the free market and private companies for taking care of these roads. The problem is that the way these projects are assigned are not always completely understandable for the general public and often, the abuse happens on that level. By making the selection and payment process more clear to the public, one can avoid these issues however. E.g. the COTS and commercial crew competition and fixed cost way of using private companies for space access, versus the old cost plus single provider way of doing things for the SLS.