An old adage goes, "Employees feel they don’t make what they are worth and employers think their employees are overpaid." One explanation is employees may measure their contribution in terms of their potential. Managers instead, tend to measure outcomes. The discrepancy in potential may be as much as fifty-percent.
There may be any number of reasons employees withhold effort. Some cite the work is boring or they feel effort is unappreciated. Others say they do not have proper tooling and information, so why try. Whether or not a manager feels these or any other reasons are reasonable it is in the companies best interest to resolve the issues.
Many times such issues are "resolved" through fear and intimidation [F/I]. A "quit whining and get to work or else" attitude may drive the discussion underground, but the problem will be far from resolved. Employees go through the motions and deliver that which is measured and rewarded, and very little else. The F/I style manager may even think this is great. Thinking-employees, offering suggestions and contributing may make them a bit uncomfortable?
My feeling is this is short sighted and the cost to business is incalculable. To get a glimpse of potential, watch an employee away from work, doing the things they enjoy. Effort invested in making jobs more appealing is an almost untapped source of profit. Creating joy in work is often as easy as removing the things that prevent it.
In this respect employees are a lot like clients. The absence of complaining does not necessarily indicate satisfaction. I feel making a job more enjoyable is not only good for employee retention, it may also be a way to see more potential than many think possible.