Those trailers are very common in The Netherlands! Weather doesn’t play that much of a role, from what I know, neither does the fertility rate as cycling has be

Those trailers are very common in The Netherlands! Weather doesn’t play that much of a role, from what I know, neither does the fertility rate as cycling has been popular here when it used to be much higher, decades ago. It is very much a cultural thing in my experience. Nearly all children go to primary and high school on their bicycles, by themselves, although the trips for high schoolers are often < 8 km I would guess. I think that touches on why it might not be as popular in other countries, as other countries might not be as flat or lack city planning that takes cyclists into account, e.g. dedicated bike lanes. It’s also an excellent choice for a country of our size that has limited space, as bicycles make much better use of it than cars.