the "charity begins at work" problem

i thought this was a very enlightening article. i didn't know that there was such a big debate surrounding the charity/corporate work. how do most design firms decide how much charitable work to do? the only background i have is Dawn Hancock with her firm, Firebelly designs. they choose one non-profit group per year and they do any work the group needs done. the only thing i was really confused about in the article was when they talked about overprinting new information on old posters. wouldn't it still cost the same because you have to make the original posters in the first place?