If I understand the situation correctly, workers from other provinces require a permit to live in a different part of China.
No, this is wrong. No permit is required. If you move to a different province, you cannot use social services, such as hospitals, subsidized housing, and public schools, but you can live and work there. Use of the social services is NOT tied to employment. Instead rural workers just get screwed and there is nothing they, or their employer, can do about it. They pay taxes to support services they cannot use. Furthermore, this status is hereditary, so even if someone is born in the city, they still are considered "rural" if their grandparents lived in the countryside in 1949.