Because most companies are already close to paying this now.
There is a reason why larger companies try to push the government for higher minimum wage, they use it as a tool against competitors, especially smaller ones. S-Mart, for example, can eat the cost of a minimum wage hike, but that would destroy mom and pop competitors in most markets, so the wage hike is washed with their taking out a competitor. As long as they stay ahead of the game and buy the right agenda, they can manipulate it in their favor-
aka, Cronyism