http://hrexecutive.com/leveling-the-playing-field-for-older-workers/
Ultimately, age discrimination persists in the workplace “because too many people think age negatively
affects ability. It doesn’t,” says Ventrell-Monsees. “People used to think that women couldn’t do certain
jobs, and most now recognize that is both wrong and not true. Ability varies considerably from one
person to another of the same age or the same gender. That’s why the law requires employers to judge
people based on ability, not age.”
Imagine the outrage if people in the workplace discriminated against the opposite s-x, ethnicities, religions, etc. that way that folks still openly and persistently discriminate against older employees.