Question: "Even though the value was comparable [cans of sodas and a dollar] --and thus the situations were supposed to be equivalent--people responded in opposite ways. Why is that?" Answer: Sane people leave six packs of sodas in refrigerators so the sodas get cold and in case those with access to the refrigerator get thirsty. The old idiom applies: treat others as you would want to be treated. Dollar bills general…
A better experiment might be this: Leave the door to a locker open, with a few items of clothing to show that it belongs to someone. In one version leave an open jar of candy. In the other, an open jar of quarters.
I suspect that some of the candy would disappear while far fewer of the quarters would go.
Of course, the reason for that is that the candy is much more tempting than the quarters, though less that 25 cents per piece.