I've actually been having much this same discussion with some buddies on FB the past couple/few days. One of them brought up the point about the number of jobs that would have their value destroyed by paying FF workers $15/h. They exampled CNA's making on average $12/h. Why go get CNA training if you'd make less than a FF worker, right? So the CNA's would have to get a raise, which means the RN's need a raise, etc. The ultimate costs to maintain employment value would be in the billions of dollars.
My personal experience just doesn't fit with this situation or the min wage thing - My middle son graduated HS last fall, worked at McD's for 6months, and got promoted to manager. My eldest graduated HS 2 years ago, he worked full time as a busser making $10/h, and part time as a mechanic's lacky for $15/h his first summer after; He's now working full time in mechanics and making $19/h plus they said they'd pay for his certifications and stuff after he had the required experience time. Hell my 13 year old got a job in customer service making $9/h last summer.
I personally just don't get why these folks are working low pay fast food if they're trying to support a family (or min wage trying to raise a family) and I can't help feeling that they are doing something wrong/poorly/etc. at work. What is preventing them from getting a better paying job?