The title pretty much says it all, but let me elaborate. I don't know about you, but in my state a McJob means you can't afford to live pretty much anywhere. Handing me $400/week would be akin to telling me to F myself really, as that wouldn't even pay the rent and utilities in a neighborhood where you'll literally hear gunshots every night.
I've noticed many/most people at these jobs aren't self sufficient. They're not supporting themselves, rather they often live with family and/or are on state assistance anyway. So it begs the question, why even bother wasting your time slaving away for a pitiful wage that is effectively useless?
Quit your McJobs en masse, grind the gears to a halt. Then you'll see change.