There are two types of employees in America. One type is called "employee at will" (under a law called Employment at Will) and the second is an employee who has a contract (like in a union, the military, or professional athlete). For an employee at will, the employer can change the work duties or add duties (that are reasonably related to the original job description). Is this fair? The employer (or the employee) can also terminate the relationship at "any time, with or without notice."
Also, there is a law that requires payment for employees (among other things). It is called the Fair Labor Standards Act (FLSA). Do you think that the average employee should know their rights regarding the money they are legally entitled to?
With employment at will, why would an employer ever need an arbitration agreement? Aren't their actions covered under employment at will?