I didn't allow mine to roam the neighborhood alone and that was 20 years ago. It is never a good idea, imo. It didn't cost my kids their freedom to not be alone, but I swore their photos would never end up on a milk carton. We practiced safer alternatives than running around by themselves. I didn't find it was in any way detrimental to their mental health or stability in the long run. It was common sense and the way I protected them from many things...not only predators.
You are right. There's way too much out there that can happen to a kid nowadays. But, I have so many fond memories of exploring or riding my bike all throuhg the neighborhood, visiting neighbors, either alone or with another friend. It really allowed me to develop my imagination and feel free. I used to go the public school after hours and make mud villages, alone, for hours and sometimes talk to the janitor there. My little friends and I explored drainage ditches, railroad tracks, abandoned houses, contruction sites, empty fields and sewage systems for hours. We had a blast. I rode my bike up the driveway of each house in our subdivision pretneding it was a car and I was shopping, getting gas, etc. I also played post-apocalyptic escape from the re-education camp, alone, using the local school and running and hiding through the neighborhood. Also lots of fun. I was weird kid!
That was 30 years ago but I really think things were not much different then except there was not as much emphasis on the adbuction cases in the news. I was damn lucky and I cringe thinking what could have happened to me, including accidents, etc.
In fact, at age four, I just escaped being kidnapped by a child molester who stalked me as I came back from a friends house. My mom had watched me walk to the house down the street but the garage blocks the front door so she could not see if I got in or not. I didn't. No one was home. But I sat on the porch waiting for a while. My mom thought I was inside playing. After some time, I decided to give up and go home. That's when the pervert stalked me and tried to lure me into his car. My mother's instinct saved me. She was doing laundry and suddenly went cold with dread, gasping my name. She ran out and saw me standing confused in front of an old guy in a station wagon. My mom grabbed me and then chased that *advertiser censored* for miles. Turned out he was a convicted molester (two times). I think he would have killed me.
But, most of my friends and I were very savvy about the danger of abduction. My parents really drilled me after the abduction attempt. I was paranoid about it and when I played outside (it was awhile before my mom let me out of her site, though), I was alert and ran if I saw someone I didn't know.
Unfortunately, many of these kids are taken and killed by people they know. It's hard to protect against that unless your kids are always supervised. Also, a six, seven or 8 year old can try to run, but a bad guy can easily overtake them. It's simply not a risk I'd take with a child of mine with what I know today.
I still think it's a shame though. My uncle at age 12 in the fifties in Western Australia camped with a friend for days, by themselves, in the outback. It was common then. Can you imagine the fun, the adventures they had? I'm sad for kids that such freedom is no longer possible.