Not true. Probably 10 years ago my kid and two friends played in each other’s yards mostly unsupervised. Only led to one ER visit with a scratched cornea (my kid). But yeah, mostly there are always parent(s) around. 40 years ago I’d disappear for hours with my friends every day in the summer. That doesn’t happen much today.
Not true? Ok, when was the last time you saw a collection of kid-sized bicycles outside the local grocery store, convenience store, or local blue plate joint, with a gaggle of obviously unsupervised kids inside? For that matter when was the last time you saw a group of obviously unsupervised kids anywhere? It's telling that you think a couple kids hanging out in their own yards clears the bar here. If I were to hand my 11 year old a hundred bucks and tell him to be back at sunset how long do you recon it would take before I got a phone call or a visit from the police?
> when was the last time you saw a collection of kid-sized bicycles outside the local grocery store,
Every school day after three in the afternoon - so, half an hour ago (it being 3:30 pm here in Australia GMT+8).
I can't speak to your 11 year old, but I'm happy leaving my grandkids with money .. typically I've let them (and my kids when younger, nieces, nephews, et al) pull molten glass from a furnace from 5 onwards (with half an eye watching from not too far away), relatively unsupervised after they've left primary school.
First year high school is typically 12 or so (IIRC).
Chainsaws, angle grinders, etc. are definitely a high school thing, as is riding bikes to the beach and free diving with a gidgee .. as long as they bring back fish.
Is playing in your own yard really "unsupervised"? Similarly to you, when I was a kid (in the 90s), I would leave home on my bike after breakfast and come back before dinner. I was maybe ~10yo. Now that was unsupervised.