Cockroaches are nocturnal and need to have a place to hide during the day. They can easily hide under pine straw, fallen magnolia leaves, leaf litter, bricks, and in wood piles. Of course it is almost impossible to find them far from human habitation. Great numbers of cockroaches cannot fit in small cavities under pine straw or leaves. Large protected cavities are the kind of high-rises that can support massive densities of cockroaches, for example tree holes.
Some cavities can easily accommodate thousands of cockroaches.
You may occasionally see them inside your house, but only rarely. That's way too dry for smokybrown cockroaches to thrive, since they sweat so much. The cockroaches you do see inside wandered in during random exploration and they couldn't find their way back out again. Many people often see them turned over on their backs after they have died of thirst and dried up. In the rare cases where there are large number of these cockroaches inside your house sharing the living space with you, there must be some structural flaw in the building.