The idea of fast food (unskilled and untrained) are worth $15 an hour plus the burdens of employment (about 20%) is ridiculous.
There is a reason why McDonald's ordered 7,000 tablet order devices for its euro stores - they will get the bugs worked out and replace the people here who believe they should earn FAR more than they are worth.
"What difference" "does it make?"
I think they'd probably be a lot more successful, and garner a lot more support if they were asking for something more reasonable. $15/hr is nearly double what they're making now.
If you build a man a fire, he'll be warm for a day.
If you set a man on fire, he'll be warm for the rest of his life.