The market already limits worker hours when left to its own devices, no intrusion is required.  Long hours which reduce worker effectiveness already make a business less competitive. The invisible hand will remove those businesses which exploit their workers, or who don't take into account employee motivation and what they need to get maximum productivity far more effectively as they are beaten in the marketplace by those companies which do take those things into account.  Improvements in worker conditions always come first from the private sector seeking to maximise profits. This has been true as far back as the industrial revolution.