Reading your text, it was mentioned that your friend made a mistake just because of carelessness. This is also a big organisation. Therefore I got a feeling that this company do not allow employees to make even simple mistakes.
American companies especially, when an employee is on the ball, occassionally, the boss will give him a pat on the back, given an increment or incentives. He may be the best employee and yet when he makes a simple mistake which is not to the boss liking, he may be given a warning, demotion or even dismissal. That's it. It's unfortunate.
Some Companies may have office politics which is bad, but common. Good employees in the eyes of the boss may be bad and finally condemned. Those who knows how to make the immediate boss happy may be rewarded.
:)This is life. Being able to adjust, make the correct move and move forward is essential in today's commercial world.
The most important thing is not to look back. Always look forward. What happens yesterday is past.
Just my simple thought.