The food service industry is known for its unpredictability. Some days are busy, some aren’t.

And workers often quit. About 70 percent of all employees leave their restaurant jobs voluntarily, according to research firm TDn2K.

But new laws are mandating predictability for some food establishments, leaving many businesses with extra costs and a sense that the rules create an uneven playing field.

Four cities and the state of Oregon have enacted predictive scheduling legislation that penalizes fast-food or chain restaurants if they don’t schedule employees with advance notice. San Francisco also has predictive scheduling laws but they apply only to...