No, it is the default of the law. They don't need an employment agreement. See the links in my replies in this thread. The laws says the own nothing...EXCEPT...

No, it is the default of the law. They don't need an employment agreement. See the links in my replies in this thread. The laws says the own nothing...EXCEPT...anything related to their business. They are being generous (or maybe just trying to make sure people don't quit) by signing agreements that let you out of the default law.