The reason is simple: you don't understand the law, and particularly the authority of law. For whatever reason, you have not educated yourself on this topic.

It has been repeatedly declared by the courts of this land (America) that an enacting clause is to appear on the face of every law which the people are expected to follow and obey.

Here, I will help you out; if you are in a rush then simply read the last page or the chapter entitled "Our Nonconstitutional Legal System", but do read the entire document if you can:
http://econcurrent.com/devine/files/08-Law/Authority%20of%20Law%20part%202.pdf