I work in fast food and i kinda got a run down on how it works. You see, the little restaurants are put in towns and owned by one guy, who usually hires managers to run the restaurant. McDonalds, Arbys, etc is kind of just a brand name for places. The big guys up top don't give the individual restaurants money. each restaurant has to support themselves. They have to pay for wages, bills, and the cost of food.
When something like min. wage is increased, its making it harder to keep the restaurant running, so in turn, you have to raise the prices on the menu, which could very well make people stop going there.
Raising and lowering the min. wage is a terrible idea. sure, raising it tiny bits at a time is ok, but not by $5-7.
This is kind of a simple way of explaining it.