There are many businesses that count on and need government contracts to maintain or to thrive as a business, to which government contracts obtained may be city-issued, county-issued, state-issued, or federal government-issued. The nice thing from their perspective about said contracts is that the government’s ability to pay is extremely reliable and almost a certainty in nearly all cases. Having a value client that is known to pay their bills is always a high desirability, made even more valuable by the fact that government contracts can be suited, in some cases, almost exclusively to a given vendor.
The structure of government contracts varies from fixed price, to cost plus fixed fee, to time-and-materials, to a truly negotiated contract with a multitude of contractors that are eligible to bid on said contract. Government contracts can also be set up in such a way that only one possible vendor can win, simply from the basis of the Statement of Work, or also through nefarious avenues that eliminate any other potential rivals. In situations to which the government contract is essentially sole-business set aside, there are massive opportunities for corruption on both sides of the table, and it is human nature to expect such shenanigans to happen.
The best government contracts have a clear Statement of Work, that allows for more than one vendor to quote upon the nature of the work, with a given transparency to the public so as to show the winning bid and the justification behind the winning bid, if, for instance, the contract is awarded to a vendor that has a higher price or for some other reason that justifies some explanatory words. It is also clear, that the more transparency that is provided to the public or to its constituents that are knowledgeable about the nature of the work, or to the press in general, the better the chances are that the contract being issued is, in fact, fair. The corollary to this is also true, in circumstances to which information about a given contract is obscure, designated as a "secret" for security reasons, or the like, you can rest assured, that the taxpayer, in general, is getting a raw deal.
I am always amused when I am driving around town and see some road sign to the effect that the work being done is an example of "my tax dollars at work". As a taxpayer, you do not want to take these things on faith, instead you want to believe that the "invisible hand" of the marketplace is doing its efficient job, but that can only occur in a truly open and competitive marketplace. Unfortunately, it is often up to the public to monitor and watch their public servants, because too often, these servants of the State, far from having an abiding interest in doing the right thing for their constituents, find it more to their liking to work hand-in-glove with corporations and contractors in such a way, that the benefits accrue to them while on the job, in addition to setting the table for future consultation or employment with these entities when they retire from public service.
My experience is that when dealing with other people's money, or other people's property, your interests are not going to be aligned the same way as they would be as if the money was your own, consequently openness, knowledge, experience, and transparency are the only hope of achieving some degree of fairness and efficiency.