I think for many Americans, work is life. You get up, you spend an hour in the commute to work, you spend your 9 hours at work, you spend some more because overtime is expected, you commute home, you watch some reality television and go to bed.
At work you have made friends, you spend time browsing the internet, following up on your hobbies, etc. This is where life ends up happening. 8 hours consumed by sleep, or the avoidance of sleep, 3 hours in the process of getting ready and getting to and from work, 10 hours of work. When you're at home you're too tired to do much in the way of hobbies, so instead you do the few things that you're not going to get away with doing at work, maybe you have a drink, play video games, watch TV. But hey, maybe your work has a facility to let you play video games and watch TV anyways when you're working overtime. So instead of getting home and doing things for 3-4 hours, you stay at work with your coworker "friends" and spend your time knowing that if you want to take a break, there is a break room right there. You don't use it for those 4 hours, but you know you can, you know, if you weren't so busy, or if you really need it.
Contrast that to somewhere like Germany, which is where this article was written. Work days end early. The culture in Germany is not to live at work. Work is for working. You come to do a job, not to have interpersonal relationships with co-workers. The average work week in Germany is the lowest of all OECD countries at 25.6 hours per week according to a 2011 study.
I think the reason that Americans live to work is not because of something specific to Americans, but rather that workplace culture demands that Americans spend so much time at work that their work BECOMES their life. I mean, if you are working 80 hour weeks and commuting, and actually sleeping, it's impossible to have a life outside of work, but we need to have a life, so that life takes place at work.
So when Americans work more, they see their associates more, they are in the environment that they're most familiar with, they are basically at their home. On the other hand, when Germans work more, they are away from home.
I guess the question is which is better for people, and which is better for industry. Germany's industry is doing well, and I think that with shrinking demand for human resources, a more efficient, but shorter individual work week is a better long term scenario. It would be a big cultural shift for something like that to happen in the US though.