Since then, any and all cash donations, given on site at the pantry itself, are funnelled to United Way. The pantry never sees a single cent of the money and United Way does not provide any food (UW employs two people and sends a truck periodically that delivers food from an unaffiliated food bank). No one who works there has any idea where the money goes or what happens to it. The employees there are not allowed to explain this to donors. The donors, of course, have no idea either.
The pantry is only allowed to keep tangible foodstuffs that are donated directly to them, which they can then give to people who need it. The pantry often runs out of certain types of food. When they do, there's nothing they can do but hope someone will donate more of that specific item, meanwhile watching as the cash donations that could be used to buy it get sent away.
I realize this sounds implausible and I can't cite any sources for it[1]. Just be careful about the assumptions you make regarding where the money goes. Food is food and people can eat it. Money can get funnelled or turned into other things, and unless you're there to watch it happen, you don't know what's going on.
[1]: Howevever, if you haven't already, read the Wikipedia page on United Way sometime and see if you can figure out what it is that they actually do, other than collect money, build bureaucracy and get involved in major scandals.