As a sailor I have been all over the world.
My impression is not that Americans are the most overworked.
It is anyone who works for an employer who is un-righteously demanding, due to what you say, their greed-the employer that is.
It also affects employees who are hell-bent on promotion at the expense of everything in their lives, friends, loved ones and especially co-workers.
This may be more prevalent in America, I am not sure, because I have been to plenty of businesses here where people are treated well and behave well.
In my last job, corrections, I was in an unbelievably demanding environment, in many ways it sometimes rivalled high optempo tasking I saw in the Navy. However, I knew many people working in other departments in my state that had easy going environments who did not have the pressure on them like we did. This was government work, so, the need for crazy expectations may be hard to accept, yet, it is true. None of us were making much of a profit, but the greed of those in charge, to make the next promotion was mind-bending and unnatural.