[求助]一级经济学的问题

在经济学的note第182页最后一段的第三行有句话说: An increase in income tax causes after-tax wages to fall. Concequentely, workers will be less likely to work the same numbers of hours as they did when their after-tax wages are higher.

为什么税后工资高了工人反而不愿意工作跟以前一样的小时数了呢?