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.
I’m currently bringing her to that specific hobby as it’s a bit further away than the area she’s usually roaming around in, and she needs to cross one major road (connection to the highway) to get there - but I guess in a year or two she’ll be able to do that by herself.
She sometimes gets brought to school in the morning as it’s the same building her brother is in for daycare - but if she starts at a different time than him she can get there by herself, and of course she comes back by herself when it finishes. She’s also not required to take the direct way home - or could even decide to go home with friends, as long as she calls us if she’s coming unexpectedly late.