I'm not sure if there is a big cultural divided regarding wearing helmets for safety reasons.

Anecdotally it's most strongly driven by "competition" with cars:

- Small city -> Not that much traffic -> No helments

- Big city with lacking bike infrastructure/no strong biking culture -> A lot of close encounters with cars -> Helmets

- Big city with established biking culture -> No helmets

I think you have an inherent bias in your examples. There are bike riders outside of cities.

If you mean rural travel between small cities/towns, that's what I head in mind too with the first example (as that's the setting I grew up in).

If you mean sport biking (race, mountainbike, long distance), then you are right that I didn't consider those.

Since they don’t bicycle, you mean?

No, the ones that do bicycle frequently don’t wear helmets. The percentage varies widely based on city.

Yes, they just need to magically shrink the distances between cities