Most fast-food workers can't easily join a union, because they don't work directly for their parent company, such as McDonald's or Subway. Instead, they work for individual franchise owners, ensuring that each individual fast-food outlet would have to organize and win union recognition separately. So there's not one central employer to bargain with, as in a traditional union campaign.

A September 2015 poll found that, by a 3-1 margin, voters are more likely to support political candidates who favor raising the minimum wage.

When workers make more money, they respond by being more productive in their jobs and are less likely to leave, reducing turnover costs. This puts money in business' pockets, and workers also then have more money to spend in the local economy.

Fast food also has a uniquely difficult business structure for workers to achieve better wages and working conditions.

When families can afford the basics, they can reinvest in their communities, and higher wages means a broader consumer base for businesses.

The fast-food industry is notorious for employing millions of Americans at poverty wages.

The minimum wage isn't earned only by people working at fast food restaurants and in service industry work - the average income for positions like nursing assistants, preschool teachers and paramedics are all under $15.