The reason so much lock breaking occurs is either because the player that wants the lock broken doesnt want to wait, or the player that is getting their lock broken doesnt cooperate. This is to please the player quicker. I always check the contents of chests before I break them open (with a command, mods can not take things out of locked chests.) If it has value then it can wait for the player to log on and get the items, if it has stuff with no value, then it will probably be broken. The items from the chests do not go to the mod that breaks it, but the player that owned the property being rented etc.
PS Private signs do not work on iron doors anymore, idk why.