Puzzled by Food Collections

Here and there one sees containers in which people are bidden to place food for the hungry.

That seems strange to me. Do people contribute odd tins that have long lain neglected in dark corners of their pantries? If so some of the food may be too old to be edible.

On the other hand if people buy tins of food specially to donate them, it would be more useful to contribute money. With money those running food banks could buy whatever was most needed, negotiating lower prices by buying in bulk for a good cause, and they would not have to sort a  miscellany of  battered tins.