I hate to break it to you but in the US, employees at many companies do not work more than 40 hours a week. There are two reasons for this:
1) People who can leave will leave if the work load is too high. Those who can leave are usually the best team members.
2) It does not work. Research has shown most people are incapable of producing more than 40 hours of work a week over the long term. They can do it for a week, maybe a month but after that their productivity is either the same as a 40 hour/week work or maybe even less. People are not machines and just because they are asked to do something (or ordered to) does not mean they will or even can.
One last thing, what keeps employers inline in the US is people can leave. If you are in a bad job, you can switch to a good one.
