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 don’t know that it’s necessarily that it’s “inefficient”. Moreso that it’s difficult for a language to actually stick and be useful if you’re not immersing yourself in that language. You can go to class all you want, but if you’re not trying to actively immerse yourself in it beyond class, you’re not going to learn the language no matter how good the teacher is.
It’s relatively “easy” to immerse yourself in English language content because English has sort of become the “lingua Franca” of the modern world. Something like Polish, for example, isn’t.
I’m still not multilingual, but this concept made a lot more sense to me as to why I never retained my Spanish classes when I started learning programming. There’s a huge difference between say, reading a book / watching guides / reading tutorials on a programming language (which by itself generally won’t get you anywhere) vs actually following along, trying to make your own projects, etc.
How would a child do that, if no one in their community speaks the target language, outside of the ~90 minute class?
Well that’s exactly my point. It’s pretty “easy” to do it with English because there is so much English media to consume out there. A lot of shows and movies they want to watch are probably already in English. Their parents might speak English for work, etc. Less so with many other languages.