Alison Morantz, a professor at Stanford Law School who focuses on employment law, said what made the law unusual was “its holistic approach to addressing a wide range of problems in a traditionally nonunionized industry — not just low and stagnating wages, but also employment discrimination and poor safety practices.”

“If it takes effect, it will be closely watched and could become a harbinger of similar efforts in other worker-friendly jurisdictions,” Ms. Morantz said.