Writer Lenore Skenazy tells a story about how she let her son explore New York on his own one day.

He wanted to see if he could find his way home on the subway system from an unfamiliar location, so she dropped him off in a pretty safe mall and he made his way back on his own.

When you went camping in the backwoods of Georgia, I'm sure your parents allowed it in part because they were confident in the ability of you and your friends to navigate your environment.  A city is just another environment with its particular opportunities and dangers, and a kid confident in navigating the city environment will be much safer miles from home than a kid a few hundred yards into the woods for the first time.