Because "voluntary" is only just that as long as you have many other options and can easily get away from such a place. In most industries that kind of job security/market fluidity that just isn't the case. Workplace standards are there to protect workers from being exploited. In much of Western Europe the work week is standardized to 40h/w.You can work overtime, but only within certain boundaries for shorter and longer aggregated periods to avoid every day being crunch time.