The building physics of modern hives and tree caves could not be more different from each other:
In tree caves the temperature and the humidity stays stable due to the buffer effect. In modern hives there are large fluctuations in temperature and humidity due to the lower wood mass.
The trees buffer the humidity partly in winter and shed it as a result of the ventilation of the bees in summer. Condensation only occurs in the lower edge areas due to the high thermal insulation. In the thin-walled beehives, the water already condenses during honeycomb construction. There is no relevant buffer for humidity available.
The problem of condensation in honeycomb construction caused by the poor thermal insulation of the hives could be alleviated by water vapor diffusion. In modern bee hives, however, vapor diffusion is prevented at a decisive point (at the lid) and is used only slightly on the side walls. The wood mass of the hives is too small for a significant buffering effect. All that remains is ventilation to remove moisture from the hives. The air exchange rates required for this are not achieved to some extent; condensation water accumulates in the hives, fatally already in the area of honeycomb construction.
The thermal insulation of tree caves is excellent and it can certainly keep up with houses built by humans. In comparison, the thin-walled wood constructions of modern hives offer low thermal insulation.
Hives made of plastic or polystyrene are nearly as efficient as tree caves. However, their disadvantages with respect to moisture and natural habitat can be regarded as a no-go for natural beekeeping.
Plastic and polystyrene hives can keep up in this respect, but are excluded as direct walling of the bee chamber in a species-appropriate beekeeping according to my understanding. A combination with wooden hives, for example as an outer insulation layer of the side walls, would make sense in my opinion.
In the following, you will find several exemplary calculations which illustrate the different properties of modern hives and tree caves.