More serendipity. It turns out that a number of essential oils, including cedarwood oil, are toxic to the fungi that grow on skin and that grow on leather. So someone who uses shoe trees that express such oils may have a lower risk of athletes foot and fungal growth in the shoes themselves. I am going to stick my neck out not very far and suggest that one would have to search far and wide to find an American who pays multiple thousands of dollars for hand made bespoke shoes but does not religiously use shoe trees. In America, these would likely be made of cedar. Thus, they would reduce their risk of fungal contamination, not because of an inherently superior construction of the shoes, but because of the way they maintained them.
I aslo suspect that the typical man who wears Lobbs or bespoke shoes has a large rotation and allows much more than one day off between wears of any given pair. This provides many days, perhaps weeks, for the last bit of extra moisture to diffuse to the surface of the leather and evaporate. So fungi may rarely get a chance to get established in than man's shoes. Of course, not all shoe trees are made of such wood, and some are covered with varnish that, I assume, would limit the amount of essential oil that reached the leather. So I am not suggesting that differences in fungal growth are due entirely to cedar, but I suggest that the maintenance practices of people who wear expensive shoes contributes.
My athletic shoes are, as best I can tell, 100% synthetic. It is possible there is some cotton in the mesh, but I doubt it. They have open mesh on the uppers, and even holes in the soles, covered on the inside with mesh, so they are amazingly well ventilated. I keep some pairs for non-athletic use for when I can get away with running shoes. The ones I use for workouts get saturated with sweat daily. I can rinse them in the shower, or if needed, every now and then toss them into the washing machine. I love the airiness and easy maintenance. I have had them for years, and the contents labels have worn to the point of being unreadable. For their purpose, it is hard to imagine anything made of leather even approaching this performance. But of course, they are not dress shoes.
If I were to get some shoes from DWF I would absolutely maintain them as he suggested. But in real life, I wear decent shoes, but far from bespoke. They are volks shoes, made for the average working person, who could never imagine paying the price for high end RTW, MTM, let alone bespoke. They are bought used and cheap. I endeavor to spend as little as possible on them going forward, so I use sole protectors to cover the leather soles. If this really raises my risk of athletes foot, so far I have gotten away with it. I do use antifungal spray right after I take them off, before I insert the shoe trees. I enhance the trees with a touch of extra cedarwood or lemongrass oil from time to time. Crossing my fingers.