That graph plots gross pay (x-axis) against take-home cash (y-axis). The far left of the graph (in green) shows people making under 20k taking home more than their “earned” pay. At the extreme bottom is somebody making 1,000/year taking home 10,000. The progressive income tax starts at 20,000.
Not labeling the axises does make it hard to read.
Bob Barker only died a year ago. I thought for a long time he had gone in, like, 2010 or so.