I believe that Americans are working longer than 40 hours a week because they are motivated to outcompete their fellow peers. The job market today is very competitive and in order to keep your job you need to be outperforming other workers, while your company may be looking to get replacements with some younger workers right out of college who are fine with putting in the extra work because it is one of their first positions. This motivation to is driven by pressure from peers outside of work who may all have jobs and who may be getting promotions. The competitive nature to want to succeed over your peers( who may not even be in the workplace) can push individuals to strive and work harder so as to prove that they are earning a better position. Also, some jobs just require too much work to be done that it would never get completed in an 8 hour period regardless of how hard you work in those 8 hours.