This is really not representative for other Western countries. Where I'm from, I would say that 75% of 6 year olds walk/bike to school alone, and 100% of older kids do.
> In physical space, Western children are almost comically sheltered.
I think the author should stick with "kids in the USA" when he means that.
I'm in the US and my almost-6-year-old and I bike to school together. We're exceptional in this regard - I don't see anyone else doing this and other parents are constantly commenting (positively!). It helps that he and his newborn brother are six years apart. Other families of our SES generally pump them out 2 years apart and move the brood around in a wagon for ease of supervising the oldest, while we had the luxury of forcing him to walk places without worrying about any other children's schedules.
I'm almost more worried about him managing his possessions at the endpoint than the ride itself. Locking the bike up, actually bringing his backpack in, etc.
Although I suppose I'm also a little worried about cars not seeing him at stop signs since (unlike me) he's below the hoods of a lot of cars.