The fact is, there are innumerable factors that affect people's decision-making in situations like this. The ability to decide whether or not a course of action is ethical is greatly affected by what your competitors are doing, groupthink, incentives, time pressures, etc. I could keep going. And yes, your ability to "get away with it" is also a factor.
Now you may say, "Who cares what the factors are? A wrong decision is a wrong decision." And you're right. However, as a practical person who wants to see real change come about, I cannot be satisfied with the run-of-the-mill, "They did it because they're evil and untrustworthy" response.
People are rarely inherently evil. I find it hard to believe that this group of engineers is really so different from you and I. It's likely that all of us grew up in similar environments, have gone through similar experiences, and possess similar moral beliefs. So aren't you the least bit curious why they're capable of making a decision you could never imagine yourself making? I think simply dismissing them as untrustworthy people is an irresponsible and short-sighted reaction. Human beings are more complex than that.
A lot of teachers believed that the only students who cheat are the dishonest ones. Well, some clever psychologists came along and -- lo and behold -- they showed that under the right circumstances, you can convince almost any student to cheat. That's the nature of humans.
Like it or not, we react to situations much more than to our personal moral codes. No amount of shaming greedy bankers, book-padding executives, dishonest politicians, privacy-invading programmers, etc is going to work. If we want to effect real change, we need to change the systems that allow for and incentivize this type of behavior.
I highly recommend reading up on basic human psychology. Influence (by Robert Cialdini) is a good place to start. Charlie Munger's writings, although unorthodox, are also great.