Zip ties are used not only by police and government enforcers. They are also used by kidnappers, terrorists, home invaders, rapists, and other nasties.
The need to escape from these ties is therefore something people should know.
The Art of Manliness created an infographic on how to escape. How to Escape Zip Ties from Art of Manliness (Art of Manliness)
ITS Tactical has an article and a series of videos here: Here (ITS Tactical)