I have thought about this a lot. I pass my elementary school on my way to work each morning. As kids we just walked there it was a 10-15 minute walk. At around the 4th grade we took our bikes. We were accompanied by our parents the first week or so and then just walked in groups. No danger, no incidents, nothing. And this was true for all kids that attended the school. There were maybe 3 out of the 40ish kids in my grade that lived too far away and arrived by car. These days...there's traffic backing up all around the school, every single kid arrives by car, the thingy where you can lock up your bikes is completely empty.
Our days as kids looked like this: Back home from school, lunch, play until the night...usually outdoors wherever we found interesting stuff. No set dates or sheduling, you just walked over to your friends house and figured out what to do, maybe pick up a couple of other friends. If someone wasn't there you just tried the next house. The activities involved climbing trees, building your own boat to paddle on a small creek and other things that would be considered deadly activities these days. Lots of sports and getting dirty, too. Surprisingly enough no kids got abducted. On the flip side I watched very little TV (we didn't have a TV for a decent chunk of my childhood) and I didn't have any computer for a good chunk of my childhood either.
I also think parents spent more quality time with their kids "back in my day". Family trips to the zoo or just playing football in a park or something. I see these parent/kid teams a lot less these days. It's a very strange development because the benefits seem so obvious to me and the "downside" is spending more time with your kids or letting them do more things they enjoy.