Minimum wage laws present a knotty problem. On the one hand, pie has a good point about it being unfair for taxpayers to be forced to subsidize Walmart's low wages. On the other, there are plenty of people who will be priced out of the labor market by a higher minimum wage. That is the whole reason for those subsidies, we want to make it more attractive to work than draw welfare.
The left always wrings its hands about a liveable wage, supporting a family etc, but in reality the vast majority of minimum wage workers are students and others who are doing part time work. They also ignore the fact that someone flipping burgers today can be managing that burger joint in a few years if they are diligent. Keep bumping up the minimum and you will have robots flipping those burgers.