I remember very well the frustration I felt when I saw my father drop a twenty or two in those box. Especially since I knew very well we needed those bucks more then the big shots up there. He always fell for the "please donate generously with your heart" speaks and of course the nice smiling sisters sitting next to the box helped.
Just knowing he still regularly wastes money like that makes me mad, so I'll just not think about it. My bet is it gives him a nice warm feeling of generosity and accomplishement when he does so. I never found the heart to put even a buck in there.