Lots of voodoo around grounding. When dealing with receptacles and utilization equipment, the most important aspect is not that the metal is connected to the earth. The important thing is that it is connected to the service neutral so that an OCPD will open if a fault occurs. Being connected to earth is just a side effect because neutral is connected to earth.
Sometimes grounding is more harmful than good. Consider a generator insulated from the earth. It will just have a receptacle on it that has a ground terminal bonded to neutral. Suppose you plug in a metal power tool. If the tool is ungrounded, there is no chance for the user to get shocked unless you get in the circuit between the line conductors. But if the tool is grounded, you basically put one of the line conductors in your hand.
