corruption is really a scourge in underdeveloped and developing countries. As you say, by people whose greed corrupts the system, and then makes others enter the wheel that does not stop turning, the contractor accepts the job because he must work and it is institutionalized that he must pay the official who awarded him the job, and so the people are cheated with a poor quality work that only serves for the politician to take pictures at the inauguration of the work.