Acually, they don't have too, as i've read, and since had a personal story related to me about.

I forget where, however there is a website dedicated to peeing standing up for women. It involves basically either just unzipping, and probably unbottoning your pants/shorts, holding open your labias, and using your fingers to aim your urethra. They also have small little plastic thingys that one can insert over the urethra which basically gives them a larger little penis to pee from.

The site also said that if done properly, it almost eliminates the need to wipe after peeing, as little-to-no urine gets on you because the labias are spread or the urine exits through a tube.