That's an interesting question, but you can replicate this experiment in a variety of ways and see the same result. My mother is a nurse, and she has a saying that goes something like, "Leave a $50 bill in the break room, and nobody will touch it, but leave a plate of brownies and they're gone before you can tell people to take one."

Since it won't cost you much, try this: Leave a box of pastries or chocolates somewhere people congregate (the lunch room, a common kitchen, etc. Probably not on the street :). Count how many are left the next day. At another point, leave the cash equivalent. Count how much is missing at the end of the day.

In the vast majority of cases, the food goes (in the absence of explicit permission), but the money doesn't.