I'm an exempt employee, but my time certainly does not all belong to my employer. I realize there are some who do, but I do not check email at midnight. My phone has a do-not-disturb setting that goes from 10 pm to 6 am. If I was asked to forego seeing my family for an extended period of time so I could, say, work on a report until 10 pm every night -- although I would try to help, any more than a small amount of this would be abusive, and I would decline to do it. If this was a real problem, I'd find another job.

Being exempt does not make me a slave. It does not mean all my creative power is used only for my employer. If I were to accept those conditions, I would have to be paid five or ten times more salary -- not even a linear increase, because the time is non-linearly more valuable to me.

I've been at a company that behaves like this. It was completely abusive of the meaning of exempt. I have nothing but contempt for companies like this.

Simple solution, at least for me: don't sign a contract that suggests that everything you think belongs to your employer; or at the very least, take your pound of flesh when you do sign something like that.

Incidentally, even the awful company above changed their contract for me when I refused to sign the over-the-top original document.