"but kids will bring home a note with the contact details of their playmate, and their parents will schedule it. The whole calendar scheduling, driving, chaperoning etc are things that definitely happens."
There are a few who walk home from my son's school and it's great to see them take 30 minutes to play or even just sit together throwing cut-grass in the air.
Actually Stranger Things already alludes to that.
Everything is too scheduled. Its hard to break out of the "if it isn't schedule, it isn't happening" model when everyone in the family is so busy. We try and encourage independence even in our youngest, but "free time" is at a premium.
NOTE: my kids aren't "neurotypical" and have lots of appointments, etc adding an extra layer of "busy"
Sadly, kids in our direct neighborhood don't generally mingle or have unschedule play. Definitely different from the way I grew up (grew up in the 90s: little to no supervision, just wandered the neighborhood.)