It's all a matter of statistics, the way I see it. Anytime you leave the house, something bad can happen. If you are small, not mature enough to confront a stranger, or out numbered, you statistically have the cards stacked against you. Having experience catching the bus alone, riding your bike to a neighbors, or running an errand down the street doesn't guarantee your future safety.
When I was 13, another girl and I were almost gang raped on a school bus after the stupid bus driver gave a group of boys some Playboy magazines to "keep them calm and amused."
I lived in an affluent neighborhood, and these "classmates" of mine were children of lawyers, cops, teachers, etc...the kids on my block who I grew up playing with after school, and supposedly the bus driver was a mom who was working part-time so she could go back to school (whatever). We lived in nice homes, went to a supposedly nice school, and supposedly had upstanding parents and families.
So after the school doing very little to remedy the situation, my parents put me in a private school in a neighboring city. There were no buses, so a group of us had to catch a city bus to school. We left our nice neighborhood and had to pass through some not so nice neighborhoods before we made it to school. One day a car pulled up to the corner where we waited for the bus to go home from school, and a man flashed us. Outraged parents demanded the school do something. Their solution? Have two elderly nuns wait on the corner with us. We got shamelessly flashed again and then some... One of the nuns went into cardiac. We finally got a private car pool van that picked us each up and dropped us off at our respective homes, because the parents realised there is no such thing as safe travel to school when you're in the wide open world and the school didn't want the liability of something happening to a student on their way to and from school. This was back in the 80's when things were supposed to be more simple.
My point? There are alot of freaks out there. Some are the people you think are "community" and those you trust like neighbors, co-workers, etc. and others are the stereotype. Bad stuff happens everyday, all around you and your kids. If you and they come home safe, your number wasn't up yet. But to blindly think that they're somehow gaining independence or learning to navigate the world because they were given some freedom is a mistake. They've just been lucky. If someone wants to hurt them, someone loses their sanity at the drop of a pin, the only thing you can hope is that they (your children) are not at the wrong place at the wrong time, are independent and wiley enough to outsmart the wacko, or have the where-with-all to play dead during a crisis situation and survive.
I think it's a disservice to yourself and your children if you believe loosening their leash is somehow giving them an edge over children of more protective parents. Reality is their freedom and safety are dependent on the roll of the dice..a matter of when, not if....statstics and probability...not gained intelligence through experience and risk.