“For every good day, there’s three bad days,” said Nichols, who has been in the service industry since she was a teenager. “You have no security when it comes to knowing how much you’re going to make.”

That uncertainty exists largely because federal labor law allows businesses to pay tipped workers, like food servers, bartenders and bellhops, less than the minimum wage as long as customer tips make up the difference. Voters in Arizona and Massachusetts will decide in November whether it’s good policy to continue to let employers pass some of their labor costs to consumers.