Some weeks are more intense than others. It happens, so what? I'll put in the extra effort, and get the job done. It helps staying motivated when the bosses are putting in the extra hours with you.
The opposite of what you call "Americanesque slavery system" is this, oh-so-common system in France, where people have no passion for their job, care only about the salary and picture quality time only "outside" of work.
I spend too much time working to not care. If my job wasn't fulfilling I wouldn't be doing it.
Disclaimer: I'm in my twenties with no family to feed, no financial debt and generally very little financial responsibilities. I don't know how long I can afford demanding having an interesting job.