As others have noted, most of the world does not follow Western society’s definition of corruption. Many places consider nepotism and cronyism the ‘proper’ thing to do. As stated in the OP, to not share is considered more shameful. And bringing shame on one’s family trumps any feeling of guilt in not following the ‘law’.
Speaking with roommates and friends from the Middle East, South Asia and China, three things I have noticed are that arm’s length transactions are not just a foreign concept, but almost alien or inhuman to them. The purpose of a deal is supposed to enrich them, their family and their friends, which includes giving them preferential treatment. They also have very different views of conflicts of interests. They are far more likely to deal with a cousin’s company rather than a independent third party. Relationships matter more than independence. Many businesses are also family-owned and so are not concerned with audits or other third-party verification.
The last bit I heard was a differentiation between ‘benign’ corruption and ‘malevolent’ corruption. In India, paying bribes is commonplace, and a cost of doing business, but generally no one is forced to pay it. The example my friend used was paying to get a telephone installed. If one pays the ‘extra fee’, they can get a phone in a few days. If they do not, they sit on the waiting list for a few months. Nepotism and cronyism tend to fall in this category also. We called this ‘benign’ corruption since it is mostly just about money and relationships.
Malevolent corruption is when someones life or livelihood is endangered. Threatening someones life or family or property unless they do as they are told - basic extortion except its by the government and not the mafia. I was told that this is very rare except in purely lawless areas such as slums and other hellholes where no ‘honest’ cop would risk their life. I’ve been told that in certain parts of Mumbai, the last people you would want to call are the police. Paying bribes is the more common method of advancement, not taking a civil service exam, which they then recoup by taking bribes from the populace.
I honestly cannot say which system is better though - the Western view of the law often leads to bureaucratization and alienation - nameless clerks that refuse to budge an inch, no matter how senseless the policy or regulation, but creates a consistency which is beneficial for long-term planning. The Asian* view creates a less active civil society, but have very strong families, which are far greater than the nuclear families of the West. The way it was put to me was that if you cannot rely on your family, why the hell would you rely on the government, as well as the fact that most families are far older than the current regimes in most of those places. If one is in trouble, a person relies upon their family contacts. Their first phone call will be to the family patriarch (or matriarch in a few cases), not legal counsel. Forget about trusting a court-appointed lawyer, no matter how well qualified they may be. They would rather call cousin ‘Vinny.’
There may be some happy medium between the two, but I am not sure what it would look like. This is one of the areas where governance studies are trying to determine best practices that would transcend borders. I am not sure if it is possible.
*I call it the Asian view since it seems most prominent in Asia, but I see the same tendencies in Latin American and Mediterranean/Levantine cultures also.