It only makes no sense if you have a simple minded view of how the MW should be set for each state. I didnt say MW should be equal across the board. I said the MW for each state should be set at a national level.
Again, it makes no sense to think that some beaurocrat in DC has a better idea what it costs to live in Miss. than the people who live there. In addition, a state minimum wage law would effect every job in that state, but a national minimum wage law would only effect jobs in companies that engage in interstate commerce. Since minimum wage laws only effect the lowest skilled worker, a national minimum wage law would not apply to most of the lowest paid workers.