I have to agree with Mr Drum on this one...

The Great $16 Muffin Myth | Mother Jones:

...So did DOJ really pay $16 for muffins? Of course not. In fact, it's obvious that someone quite carefully calculated the amount they were allowed to spend and then gave the hotel a budget. The hotel agreed, but for some reason decided to divide up the charges into just a few categories instead of writing a detailed invoice for every single piece of food they provided. 

This is unremarkable. In fact, I'm here to tell you that this happens All. The. Time. I've been involved in what feels like a thousand conferences of this kind, and I'd be shocked if it happened any other way. Hell, I'm surprised DOJ even got that much of a breakdown. Far more commonly, your event person negotiates what kind of refreshments you'll get, and the invoice ends up looking something like this:

Refreshment table (bev/morn/aft) — 5 days....................$39,500...

Yeah. I never go to conferences, but I know enough to know how it works. If you ask the hotel to provide refreshments, they don't just bring out a bowl of muffins. There's a sort of buffet, with coffee and tea and OJ and cream cheese and fruit and cookies and bagels... etc etc. And there's at least one staff person refilling the coffee urns. And extra work done in the kitchen putting it together. And people have to clean up the mess. And supervisors drop in to check up, and also spend time talking to the conference organizers. And you are using hotel equipment, the cost of which you are partly paying.

That's all paid for in the "cost of refreshments."