We had some friends over last form the US. One 11 yr kid in the group was bored and said: ok I’m gonna go home now, I need the keys please.
He walked home by himself - maybe 500 meters… For us Europeans it was nothing to notice really, but the Americans were absolutely shocked.
I don’t think you can profile this as American. Are they conservative suburbanites? My kid walks to/from school longer than that. Many kids take public transit in big cities. Rural kids may ride a motorbike much further.
That says more about the people you were with than America.
I see plenty of 11 year olds in the US without any parental supervision while in public.
I mean kids get jobs at 12?
And I've been where the Americans had some friends over from the US, and the 11/12 year olds grabbed some rifles and said they'd be back tomorrow. The Americans barely noticed, the Europeans flipped.
America is big, and parts of it can be very different.