They have strange laws in Pa! Here in Oklahoma, 14-year-olds
can get a license, not a permit, but a license to drive on public roads as long as they're running errands for the family farm. Most get around the law buy going into town and buying a bag of feed or seed, keeping the receipt handy, and then going wherever it is they might care to go.
Kids of any age can operate any vehicle on private property as long as they are big enough to operate them safely.
I venture that OK is less dense than PA. And I mean that by population, not mentality! This case illustrates the population density of NE Philadelphia. Car didn't have to go far off the school parking lot to be in a front yard. Add to that our traffic.
Maybe your laws stem from when a child was a necessary hand on the farm, too.