alt Hacker NewsThe rationalization aspect of their model can't be overstated enough in my opinion. It never starts with something clearly unethical; it starts with something more complicated. Something that is uncomfortable and morally suboptimal, but has some justification being appealed to — it benefits the group, it's otherwise unfair for some members to have to bear some small temporary cost for the benefits of others, or something of that sort. The level of the corrupt behavior becomes more and more extreme though, such that justification becomes more and more questionable, until you're left with something more seriously problematic. In the meantime, the people who questioned the slippery slope might have left, and you're left with people who aren't in a position of power for whatever reason (they're junior, or in small numbers) to question what has become clearly unethical cultural norms.
I think the article is overlooking an important category of corruption where social norms treat certain acts as theoretically immoral but in practice impose little to no social sanction for such acts. In places like India, for example, taking bribes is just standard practice. It carries so little social sanction that it’s like jaywalking here in the US. People acknowledge it’s technically illegal, but it carries so little social sanction that people don’t consciously need to rationalize it. The same thing with cheating in schools, which is normalized in India and has become almost as normalized in the U.S.