Nope. That's a personal preference.
They don't have to, but (not to be rude) some guys don't like the bush.
ANSWER: Agreed, no requirement for a girl to shave. But, what shaved girls learn is that...
same way like boys!!! Once they reach puberty pubic hair growth will occur... It varies from girl to girl... Some may have thick hair around vulva and pelvic region, and under arms etc....