Not quite correct. The condensed matter physicists do understand how they work. The problem is it's complicated so the "theory" they teach undergrads is dumbe

Not quite correct. The condensed matter physicists do understand how they work. The problem is it's complicated so the "theory" they teach undergrads is dumbed down to be more palatable. The sleight of hand comes in where, in the beginning, the "holes" are atoms in the substrate that have lost an electron which, by the time the hall effect appears, those holes are now moving but in the beginning they were stationary. In fact, in semiconductor physics as taught, both the 'electron' and 'hole' are in fact quasi-particles and only tenuously connected to the electron of the standard model.