From what I've heard, many cases of these kinds of bribery schemes are fairly widely known within the companies themselves. The general attitude is that "everyone is doing it" and any harm is so indirect as to not seem particularly unethical. For example, some government is already set to spend $100 million with X software company, so what's the harm in kicking back $10 million to the person signing the check?

Of course it's wrong but it's very easily rationalized by psychologically normal people.

If the goal is to actually stop this kind of bribery, we should give whistleblowers a 20% reward of the penalties. In other words, we should legally bribe people into reporting illegal bribery because bribery works.