The only limit on hours worked in most US states apply to jobs where a tired worker could injure others rather than themselves. Examples are pilots, truck drivers, nuclear plant operators (Homer Simpson
). Other fields like general labor, skilled labor and the trades work schedules more like Mike mentioned. 60 to 80 hours is the norm if the worker wants to make a real good living. Any move to limit hours of those jobs in the US would be political suicide. I negotiated lots of labor agreements when I was a pup and would have been skinned alive if I suggested that plant workers be limited to 40 hours of work in a week.
Elsewhere in the world, laws limiting the hours worked were not conceived out of concern for worker safety. While politicians may say that is what they are for, they are really employment laws designed to ensure that more workers are hired. High overtime means less total employees. Limiting hours to 40 (or less in some countries) results in the employer having to carry more headcount. Who can say which system is best? One where the most driven and ambitious make the most money or one where more are employed but making less. Feel free to discuss.