Power
Mostly, this one is about the power to fire. As a consultant, you have a great deal of power in narrow silos. Companies are paying you because they trust your judgment (or because someone else within the company has convinced them to overlook their distrust of your judgment).
They're likely going to follow your recommendations with regard to inventory management, corporate restructuring, casual day prohibition, or whatever else it is that motivated them to retain your services. Otherwise, why not just make the decisions themselves?