They're somewhat rare unless you have Dying World active or you have very low control. At high control there is still a lone female bandit that spawns rarely in Stokke Hills and there is a low chance for a group of katana wielding amazons to spawn in Marston Avenue (that group of 3 near the Black Gunners). That's about it for non unique random females unless control is low.
At low control levels you get extra bandit spawns that have a variety of different possible groups of bandits. One such group includes 1 male and 3 females, which is an EXCELLENT reason to start with Dying world...
You'll see spawns for those near the shops around town as well as near the Catholic church and somtimes also blocking access between zones. You don't even need to save scum to get them, if you check out a group and it's not the group with 3 girls in it, just pull back and try again until it is. That does waste time though.
This is a good reason to build faction with the Bandits. They keep control low which means lots more enemies.