Clients sometimes play the same games with themselves.
I am a consultant. One client, a very large company, insists that I book travel via their corporate travel agent, "in order to receive heavily discounted pricing, based upon their enormous volume." I don't really mind this because they then pay for the airfare themselves so I'm only billing them for hotel, meals and minor misc. out-of-pocket expenses. Consistently, the fares they pay for me are hundreds of dollars higher than what I could book direct or via Expedia, Travelocity, Orbitz, etc. I know this because I plan my travel first, then forward an itinerary to the TA to book it for me. And it is not as though they're booking Y fares -- these tickets still come non-refundable and with a penalty for change.
I mentioned this on a couple of occasions to the corporate contracting agent I'm assigned to. His explanation was that while some tickets may "seem" higher, others are lower, so it all works out to the company's benefit.
(I guess all of my routes the past two years just happen to the higher ones.) Plus, he proudly explained, the company gets "rebates" from the TA at the end of the year based upon its volume.
Ah ha! Classic purchasing/contract manager making himself valuable to the company by "artfully negotiating" these wonderful rebates to the corporation.
In reality, the department cost centers are paying higher prices up front at the expense of their individual P&L's so that corporate purchasing can pretend to be a profit center.