When I read the headline I thought they meant “and the rest walk”. Most Dutch primary schools are small and local. My school (not in Assen), back in the nineties, had a rule that you weren’t allowed to come by bike if you lived less than 1km away because they didn’t have enough space for the bikes otherwise. I always looked with envy to the kids who got to bike, I had to walk.
All I mean to say is, this is a pretty normal statistic (anecdotally) and going to primary school by other means than biking or walking happens but isn’t super common except in very rural areas or special schools (either for special needs kids or based on some niche philosophy) that attract kids from a larger distance.