I find that in an undug garden, where the mole runs are not disturbed, there is less new upheaval. In the 1980s, my acres of brashy soil were full of runs, with little damage to plants.
However in clay soils I have sometimes found they can bring up some horrible subsoil; when this happened in France I borrowed a "moletrap" and once the (one) mole was gone (killed I am afraid), all disturbace ceased.