I'm curious how this scales. In your culture, how do you deal with a thousand people in a company feeling comfortable telling the CEO how wrong he is? What happens when 500 people think one way and 500 think the other?
Lastly, you need to moderate your feedback because sometimes the CEO can take you too seriously! If you just lay out a coherent argument that something is stupid, it can look very dire to the CEO. Offering a thoughtful and slightly more optimistic alternative perspective can help a lot. I had to learn that I was unduly stressing CEOs in these situations, because they took the negative feedback seriously without proactively offering a counter-balancing optimistic scenario when that existed. The best approach is “this is won’t work but I have an idea”.
Even in cultures where this is considered normal, most people don’t do it, or don’t do it well. Constructive no-bullshit feedback is genuinely valued by CEOs at large companies. Being that person, which I naturally am, has been very high leverage across many large companies in my experience.
Our organisational structures are generally just as flat as our landscape, which might help promote more opportunities for people to speak their minds to upper management. I don't have data on this though.
A distant relative of mine always said his business would have never started making money if it weren't for the Polish ladies who worked in his factory complaining so much about their work areas. He had his lunch in the general cafeteria together with everyone else whenever he could, and that is not uncommon here.
Edit: We also have a concept called "medezeggenschapsraad" or "ondernemingsraad" (depending on context), which is a kind of employee panel with decision making power that businesses of 50 employees and up are required to have. Unsure if this is unique to the Netherlands though.
If there is a choice to be made, he should make it, explain it, and live it.