My wife and I were discussing these kinds of childhood adventures. She once missed a stop on her bus, and didn't get to school. The bus happened to drive past her daddy's office building, and she recognized it (from car trips where it was pointed out "that's where daddy works!". She got off the bus, and went to the building's courtyard. She played by herself all morning. At lunchtime, lots of people came out to eat their lunch. One person talked to her, and asked who she was and why she was there. She (happy to talk to a complete stranger) gave her name and said her daddy works here. The person got the daddy's name, daddy was notified, and she was quickly taken to school.
Likewise, I had lots of adventures when I was 4 or 5, taking my bicycle and dog and wandering far from home until I was hopelessly lost, hours later. But I always found my way home, or found someone whom I could trust to help me, and it all worked out in the end.
This generation of children will never experience these adventures, since parents are able to keep 24x7 connection to their children.
If you don't get lost in your neighborhood at age 4, how are you going to handle backpacking in Thailand when you're 21?
If you never have to look at strange adults and judge which one is the safest to talk to when you have a problem, how are you going to be able to approach a member of the opposite sex at a high-school dance?
If you never practice getting out of a bad situation when you're 5, how are you going to deal with pressure from your boyfriend when you're 16?
If you are afraid to march into unknown territory when you are 6, how will you create a new product and a new market when you're CEO at age 46?
Life is all about getting hurt, healing, and becoming stronger as a result. Kids need to live.
I don't actually blame the parents, I blame the technology. Parenthood does strange things to a person's brain, and it is impossible for a healthy parent to want a child to suffer, even if it is good for the child. I'm sure that if our parents could have shacked us with love the way current parents can, they would have. And I'm sure we both would have been worse for the experience.