You will also find more experts in the practicalities of employing children where child labour is legal (or at least
de facto tolerated). This doesn't mean that a billionaire who insist that everyone who objects to him hiring children to work in his factories is ignorant is correct, and the experts who think it's a bad idea just haven't employed enough children to know anything about the consequences.
Permanent accommodation which is multiple doors away from the nearest natural light source, relies on artificial means to circulate air and has a distinct lack of exits might find a few more supporters than child labour, but funnily enough the laws ended up in place for similar reasons. We saw what happened when we assumed that people must know best because they were rich enough to pay people to agree with them (and others were too poor and uninformed to have much choice)
What is trivially obvious is that you won't have a building design with windows in bedrooms if the person funding the design makes funding contingent on the building not having windows in bedrooms, as Munger states he's doing. In all probability the experts hadn't built masses of windowless cells backing onto windowless kitchens connected via windowless corridors to the outside world before (the reason the design is controversial, after all, is that its not exactly standard building practice in the US either) and probably had plenty of ideas on how to maximise floorplan whilst guaranteeing natural light to inhabited spaces, but they detailed this design because the person cutting the cheques told them to. Your implicit argument that a design constraint imposed by the ego of a billionaire design dilettante is likely to yield better advice than a design constraint imposed by regulators based on decades of built environment research is far from trivially obvious...
And if Munger had some insight the regulators missed, it's not exactly evident from the bizarre set of contradictions he offers up in the interview..