I thought I went so far. I thought I was so adventurous. Turns out the max I ever dared go was about 1km. Maaaaybe 2km. The distances that used to look so far and adventurous, don't even feel like a walk anymore.
Maybe that was just me, but it sounds like even if you give kids freedom to go wherever, they won't really roam that far. So maybe it's pretty safe to give them that freedom? They'll use it age appropriately.
By the time I would have roamed further than the 1 or 2 kilometers, I had discovered books and internet and computers and I was like "lol why would I leave the living room?"