Too often, the perp will then anonymously call police and report "crazy woman threatening people with a gun", describing the woman, the gun, and her car.
Net result: woman gets pulled over, her gun taken, and that's one less armed woman on the street.
Your gun should be concealed until you need it to stop an attack. You should then empty the gun into the bad guy.
Once she is convinced a threat is palpable, she should not hesitate to pull her weapon and confront him. If he's a rapist or stalker, it's not likely he's going to get police involved. He'll rush home and change his underwear.