Because it's often about the "piece of paper" cost. What I mean by this is explicit costs and savings are preferred by management: they can point to their bosses, wave a sheet of paper, and say, "See, I saved twenty-six dollars here!" In reality, it may have cost fifty dollars, but that doesn't matter. It's the same reason why we have open offices, "hot desks", and improper tools: the incentive structure is wrong.