Re: This is unnecessary
French law allows the employees' available periods to be defined,
Up to a point. It's illegal to work on Sundays and some public holidays, for example. The difference between "blue collar" and "white collar" is enshrined in law, and 'blue collar" workers have strict limits on weekly hours, overtime included.
All that leads to, of course, is people working "au noir" - illegally, outside those limits. As such they have no insurance or accident cover outside the official hours.