I am from a country where corruption is rampant. I don't think corruption is a cause, but an effect. You see certain economic schools of thought believe in the absolute power of the Market to solve issues. Corruption is the Free Market solution to economic inequality. In a society with very little opportunity for economic and social mobility and no faith in The State people will always have a market for alternative solutions to the mobility problem.

As in the article, for every engine, paid for by rich applicants, there was at least one(but probably upto 6 by my estimates) bogie, low paying applicants. Since the investigation will take years, by which time the evidence would be eroded and so would the faith in The State. Since India is growing economy with multitudes of social issues, the economic inequality would further increase inequality, creating more of a market for corruption.