Unions were a central driving force in labour protection laws and the lack of unions in the US might be a reason why you have so many people that are overworked and burn out.
Every single benefit comes at a cost. Companies do not have an infinite amount of resources to spend on benefits. The optimal mix of benefits should be determined through bottom up organic processes, not by state fiat based on simplistic assumptions.
The process by which the market develops and quality of life improves is much more complex than these cookie cutter rules assume.