Some farm managers spend their days frantically going from one crew to the next telling pickers not to pick certain fruit (or to be more careful with pruning, thinning, etc.). The crew members all agree to change their behavior while the supervisor is present, but by the time the manager makes the rounds through all the other crews and comes back, he has to start all over making it clear that he is not satisfied with the quality.
Contrast this to the manager who makes sure that each fruit bin or box is clearly marked with employees' numbers so at any time any bin or box may be inspected and the picker evaluated in terms of the quality of the work. And now add the fact that not every box is inspected, but only a few through a random sampling procedure. Through this approach, responsibility for quality is passed on to every crew worker. Even better, when there are clear rewards for excellent work and consequences for poor performance, crew leaders and supervisors do not seem to be fighting against the current.