"But even as employees frequently raised alarm, the company’s top leaders did little to prevent Walmart from being involved in bribery and corruption schemes."
Which means the "top leaders" knew of the problem, and choose to ignore it. It would be a different story if they put real effort into self policing and there was evidence they pushed the guilty contractors/etc but again:
"The plea agreement, which was technically related to the company’s improper record-keeping, ... Federal regulators said Walmart looked the other way as subsidiaries on three continents paid millions of dollars to middlemen who helped the company obtain permits and other government approvals from July 2000 to April 2011."
Which sounds more like a coverup to me.
As an individual citizen, if I intentionally failed to file my taxes properly, report crimes I knew of, or even fire a housekeeper or other low level employee I knew had been committing crimes that benefited me you can be sure I would be getting more than the equivalent of a parking fine.
That is why people are demanding someone be held responsible. It seems those that are reaping the rewards and knew of the crimes are simply being given a free pass.