There are employees who never complain.
They show up on time and follow the rules.
They don't get special privileges; those goodies go to their louder co-workers.
If they can't do something, they'll tell you, but they never whine. They are very nice people.
How are they rewarded?
They get more than their fair share of work. ["Did you finish that? Here's some more."]
They also get less than their share of recognition. ["She doesn't seem to need it as much as the others."]
Their skills and demeanor are routinely taken for granted.
That is one of the greatest sins in the workplace.