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.
This is definitely a generational, regional, ethnic, and class thing.
As a non-Asian kid on the US West Coast in the '80s, I learned to use chopsticks only slightly after learning to use a fork or spoon, even though we rarely ate food from cultures where chopsticks are standard. Heck, I’m pretty sure I was given chopsticks to eat tortellini at least once!
I was somewhat baffled as an adult when a partner’s parents weren’t comfortable using chopsticks … and they (the parents) were from New York City and had grown up eating Chinese takeout regularly.