The Gründerzeit was over before WWI. The two wars caused many changes. Even in the 1920s, many chambermaids worked for room, board, and some money.
What was possible in 1931 were utopian fantasies in 1880.
Glue and nails were expensive, then interlocking joints were used. Presumably, someone in every household in the countryside could do it. Even my father learned it from his grandfather. Many things were made for durability, not for consumption. Who can still make shingles?
We have sandstone walls in the old style, even double-masonry. Just like in the old days. One person knows how to do it and the rest help. It doesn't cost more than L-shaped stones, just takes longer, much longer. They still aren't finished.