As a 77-year-old grandparent of six children aged 7-16, I believe the essential difference from my childhood is that adults have ceased to play a general in loco parentis role. I believe this has resulted from the reduction in the age of majority to 18 from 21.
In those days, reaching 21 was a real watershed and all below that age accepted their junior status. Any "adult" would check any "child" anywhere without fear, and any accidental group of adults would act together to deal with a juvenile disturbance. There was a general perception of adult supervision, which must now be replaced by professional supervision by police or park rangers.