thanks to the incredible complexity of the U.S. fiscal system, it's essentially impossible for anyone to understand her incentive to work The second line is

thanks to the incredible complexity of the U.S. fiscal system, it's essentially impossible for anyone to understand her incentive to work The second line is true regardless if the first. Under what circumstances is $0.3, $0.6 or $.09 worth performing an extra $1 of labor? It depends on how you value your leisure time, whether you have a specific goal for the money in mind, whether your math skills are sufficient to even understand how much extra the $1 will net you, etc. That's not a reason for not simplifying the system, but it is a reason for the first and second argument to be plainly false: households do not, and are often incapable of, reason(ing) based on the fiscal system.