In my experience, American and European software developers work similarly "hard", that is not explanatory. There are noticeable cultural differences in how they spend their working time.
American software developers have a tendency toward more ambitious and therefore risky solutions to problems, which have a higher variance in outcomes. European software development seems to gravitate toward what is seen as the safe conservative solution always. You may find yourself working more hours to deal with the risks that materialize as an American but sometimes that ambition pays off and you make a significant leap forward, and I suspect there is a higher sense of satisfaction with this result when it pans out. Particularly in the west coast tech cities, tolerance for both the risk of ambitious approaches and dealing with the consequences is dialed up anomalously high, that is just the water you swim in.
With the higher risk tolerance, both cultural and what the business allows, comes a requirement to be willing to work extra hours when needed for when it blows up in your face. This is sporadic, most days they don't work any harder than Europeans. Many Americans value the freedom to take ambitious risks more than they hate the downsides of that risk-taking.
American software developers have a tendency toward more ambitious and therefore risky solutions to problems, which have a higher variance in outcomes. European software development seems to gravitate toward what is seen as the safe conservative solution always. You may find yourself working more hours to deal with the risks that materialize as an American but sometimes that ambition pays off and you make a significant leap forward, and I suspect there is a higher sense of satisfaction with this result when it pans out. Particularly in the west coast tech cities, tolerance for both the risk of ambitious approaches and dealing with the consequences is dialed up anomalously high, that is just the water you swim in.
With the higher risk tolerance, both cultural and what the business allows, comes a requirement to be willing to work extra hours when needed for when it blows up in your face. This is sporadic, most days they don't work any harder than Europeans. Many Americans value the freedom to take ambitious risks more than they hate the downsides of that risk-taking.