Neutral to earth shorthed trough a plug in a socket outlet will not trip the RCD, Can you state why please? However live to earth with in the same reason the RCD will trip. More over there is neutral in socket outlets because appliances are connected to them and they are working properly.

Neutral and Earth(ground) are at the same Potential.
A GFI will trip when the hot or neutral draws more current than the other.
If neutral and Earth are touching, and there is no load, Then, Hot and neutral are drawing same amount of current(zero volts).
If Neutral and ground were reversed, a tester will NOT show it reversed.