Do parents always tell their children the complete truth all the time? No, good parents will lie to their children to form positive, compliant behavior traits. This is true even for parents who believe ardently instilling honesty values in their children. Why would they do this? Because it simply provides a highly effective tool for controlling and training their children.
Companies lie all the time to their employees to ensure the continued success of the company. Employees don't need to have full knowledge; in fact, employees knowing too much could very well be detrimental to the company. Just look at Walmart. They have an undeservedly infamous reputation for lying to employees. Walmart is one of the nation's most successful companies. Lying to its employees allows Walmart to keep better control of its employees and wage costs low. That it turn allows the company to control costs and turn better profit margins. If Walmart had been hamstrung by out of control wage costs, they would not have been nearly as competitive. Ironically, this means that it would not have been as successful a company and would not be able to keep so many people employed.
The complete truth isn't all it's cracked up to be. Lying is actually a good thing. It serves as a useful tool for the PHB toolbox. Employees don't need to be in the know about everything, particularly when it comes to matters affecting company well-being. Little white lies keeps everyone in line, so work keeps getting done and the company keeps thriving.