Table A1 is a comparison of CAAA to NSPS, Table A2 compares NSPS to NCCSA, and Table A3 compares CAAA to NSCS.
In contrast, Figure 1 shows benefits exceed costs for moving from CAAA or NSPS to NCCSA.
If marginal benefit decreased with the more stringent standard, the net benefit to NCCSA would decrease.
Given the initial assumptions of the simulation, the lowest cost method for achieving the NCCSA standards is to adopt a CuO process along with low-sulfur coal.
The usual convexity assumptions lead to the expectation that costs will exceed benefits for the still more stringent standards of the NCCSA legislation.