Employers and employees may have different views on privacy at work because they have different objectives.
Employers consider anything their employees do at work their business because they are liable for their employees’ actions. Also, any work product employees generate belongs to the company and not to the employees. Finally, the company is paying the employees to work, not to surf the internet for new shoes or update their status on Facebook.
Employees might think that anything they do that does not concern the company belongs to them. An employee might watch a movie on company Wi-Fi on his lunch break, for instance, and see nothing wrong with that. Checking personal email on employer computers is sometimes a bone of contention, because employers will sometimes spy on their employees and even use keystroke trackers to track what they log in to. Employers may abuse their rights to employee’s information in this way. Still, the bottom line is that employees basically have few rights when it comes to privacy in the workplace.
The line blurs when it comes to out of work behavior though. For example, when a person is fired for something he posted on Facebook that had nothing to do with work, things can get sticky. Many employers have morality clauses, and some will even have employees followed. In some ways, employees are owned by the company. The company has a right to make sure the company's interests are protected.