They don't. But that's just a dance around the undeniable fact that wearing a helmet when you go up and down the stairs is safer than not wearing a helmet.
It is generally inadvisable to get within inches of a high speed multi-ton vehicle in the first place.
If something goes wrong with that, a mere helmet can only help so much, as you might expect.
I think we can agree that multi-ton vehicles are not permitted to enter houses. Because of the dearth of such vehicles, the inhabitants feel (relatively) safe, and go about their day helmet-less.
A similar approach has been used in eg. the Netherlands for bicycles. Where needed (& as much as possible, & more and more often) , bicycles are given their own paths, preferably in such a way that no motor vehicles can enter. Since the danger is thus much reduced, bicyclists on those routes also typically go about their day helmet-less.
At least, this is one way to intuit why people in the Netherlands don't normally wear helmets (as often at least: they still do when racing or mountain biking or etc where there is increased risk. Just not for the normal 9-5 commute, which is considered ~safe)
Riding a bike is inherently unsafe. What you're referring to is the proximity between bikes and vehicles, which is even more unsafe.
The roads in the Netherlands are nicely separated from the cars in most cases and also well paved. That doesn't prevent you from riding off the side of the road into a ditch and hitting your head though.
Having had a freak accident on a bike (on a safe road) and cracked a helmet, I'm sure glad that I had it on. I always ride with a helmet.
I think it depends on the type of bike and how you ride it. As far as I'm aware most dutch people consider riding a "normal"[1] dutch bike to be inherently safe.
If you're riding a fast racing bike or a mountain bike, you're probably engaged in slightly more risky activity, and people do wear helmets on those bikes.
Quick turn, front wheel slips out, head on the ground.
Bike rides off the side of the road, fall over, hit head on a rock.
Run head on into a pole.
Certainly, the style of bike helps and those are safer bikes... they don't prevent head trauma though. A helmet does.
This is also similar with skiing. I learned to ski when I was a kid and never wore a helmet. People wear helmets now. Even on bunny slopes. Kids wear them too. You're on snow, it is soft. Helmets are still a good idea.
It is the accidents you're not expecting that tend to hurt you the most.
At some point, after taking all the other measures, adding a helmet on top of all that just seems like overkill to many people in the Netherlands.
But I understand why you might feel different. I do hope you agree that the other measures should be taken too.
Just so long as it doesn't end with people thinking that just wearing a helmet makes everything ok. It's not ok if bicycle riders and pedestrians still get run over on a regular basis.
If anything, learn to set a good example for others. To me, it seems absurd to think that anyone would go so far as building nice roads for bikes, which sets a great example, and then stopping short at protecting your noggin with a piece of foam.
I'm not for mandates that people must wear them, it just seems like basic common sense to me. If people don't want to use their sense, or just take the risk on their own, sure... whatever.
https://www.reuters.com/article/us-health-injuries-stairs-id...