The point is the presence of fungal spores in a particular place. Spores of fungi are quite tenacious. If you create conditions for breeding and you are weakened, then there is a risk
Fungus is unlikely if you walk down the street. The fungus does not feel well on hot and dry asphalt and other surfaces. But by the pool or in the shared shower room, it is easy, it is humid and warm - everything is as it should.
On the street, you can get infected with worse. If you have cracks or cracks, then this is a great gateway for harmful bacteria. In addition, it is easy to injure a leg and catch an infection like tetanus.
About people who constantly go barefoot - here we are more likely talking about villagers, etc. It seems to me that their skin is several times rougher and it is difficult to injure it + due to the fact that they are constantly in contact with various microflora, they can develop immunity to many pathogens (especially if a person has been walking barefoot since childhood).