Well paid workers who are bled to the bone on the job aren't necessarily happier than poorly paid workers with more reasonable hours. They may be a better off, in many cases, but it's arguable.
- Jake If you only spend 20 minutes of the rest of your life on economics, go spend them here.
Wanting to legislate all the situations leads to heavy bureaucracy and in fine is socially inefficient. One example: the application document for the working-time reduction was 180 pages long and it didn't cover (by far) all the situations (I could provide many examples).
Legislation is necessary to provide the framework within which the collective bargaining must take place. It should fix the limits (minimum wage, maximum working time, minimum amount for training expenses...), the governance system (role and power of employees' representatives) and the methods (scope and frequency of compulsory negotiations...), but it should aim at empowering the social partners, especially the employees' representatives. "Dieu se rit des hommes qui se plaignent des conséquences alors qu'ils en chérissent les causes" Jacques-Bénigne Bossuet