Why are hair permanents not permanent? ?

The chemicals used only last for a short time, usually about 6 months, although this varies from person to person.  So colour or curl will 'fall' out after a while. 

Even if the process was permanent, your hair continues to grow, so the colour or curl will not be in the hair coming out of your scalp.

The term, 'permanent' was invented because this treatment lasts a lot longer than a rinse or hair curlers.

Think it's rice because in many countries rice is the main food so it can be traditionally served all at once.