Maybe the axis is not anonymity per se but the dignity preserved by the recipient. Anonymity is not the goal, it's a means to an end. And providing employment achieves that end even better than anonymity does.

In this light the lower levels also make sense, each progressive level allows the recipient to feel less guilty (the donor is not annoyed that they have to help, or doesn't even need to be asked, etc). The really interesting bit here is that the levels are not about how much the donor sacrifices but how good the recipient feels.