Mysteries of the Post Communist World

Wherever you walk in the  cities of post-Communist Europe, you pass buildings like these, where great chunks of the stucco have fallen off the facades:

Yet you never see any of it falling. You never come round the corner to find chunks of stone hurtling toward unwitting pedestrians. You never discover flattened citizens lying under lumps of carved ornamentation that have crashed down onto the pavement. Is this just luck or is the stuff disappearing invisibly, draining away somehow, like sand?