I was thinking about that when I was dropping my 6 year old off at some hobbies earlier - it’s pretty much expected to have learned how to ride a bicycle before starting school, and it massively expands the area you can go to by yourself. When she went to school by bicycle she can easily make a detour via a shop to spend some pocket money before coming home, while by foot that’d be rather time consuming.
Quite a lot of friends from outside of Europe either can’t ride a bicycle, or were learning it as adult after moving here, though.
edit: the high number of replies mentioning “swimming” made me realize that I had that filed as a basic skill pretty much everybody has - probably due to swimming lessons being a mandatory part of school education here.
We’re in the US and my son has been walking home from school since he was six. It’s only a two mile walk. In the mornings I drive him up to half a mile from the school on my way to work. They don’t have bike racks at schools anymore it seems otherwise he’d ride his bike. On a few occasions I’ve had him walk to school also. His older brother goes to the bus and back but that’s only half a mile away. They regularly go roam the neighborhood alone or with each other.