Germans. The basement walls are made from prefab concrete slabs with junction boxes and flex hose for the cables already in there. Thin ceiling slabs with steel rebar sticking out are lowered onto these. That's when the elec-chickens drill some holes and put in their cables, mostly in flex hose. Then the ceiling/floor proper is poured. That's how I remember it from my active time. Figure something similar is going on here. That's why the cables for the basement wiring are partly in concrete. I expected everything to be in flex-hose because that's what I could see in the junction boxes but here we are. Not very repair friendly, depending on where damage occurs.