I was raised by my father and once I was old enough to drive he didn't really care what I did. I was going to high school and working weekends and full-time in the summer. I came and went as I wanted for the most part.
I've got three kids now. My son is 19 and off to college, which leaves two girls, 14 and 10, still at home. We live in a very safe community, but neither girl goes out unless I know where they are going, who they will be with, and when they will return.
I'm usually the parent doing the drop-offs and pick-ups. They have to pick up their cells if I call and they better be where they said. Any curfew I set is early enough that they can get home, finish their chores and any homework and get to bed early enough for a good 8-9 hours sleep on a school night. On Friday and Saturday they may be out a a bit later, but not much.
Arbitrary curfews are a joke, especially if the parents have no idea what their kid is out doing and only want them home at a certain time. It's more important to talk openly with your kids, know their friends, meet their friends parents and stay involved enough to help them develop a good sense of judgment for later in life.
As for the mom who let her 14 year old daughter go off with the 19 year old guy...well, not the best parenting skills to say the least.