Who knows what fast food would be become at a 15 dollar an hour wage. I think that would force them into being automated. Seriously you walk up and push buttons for your order, swipe your card, and machines cook your burger and fries. Grocery stores would be all self check out. Why? Because you can pay a checkout machine repair man 15 bucks an hour, but probably not just some young kid who stocks the shelves.
But my friend is union grocery store worker pretty sure he makes like 20 something an hour. But he is 43 and has been there since he was 17. You can't just pay some snot nosed newcomer 15 bucks an hour.