Some additional questions I have to further understanding:
Ships don’t have ground, but why couldn’t electricity on a ship ground to the ocean the same way houses ground to the earth?
A structure will have a grounding rod dug into the earth. Does the dirt, soil, and rock composition that the structure is built on affect how willing current is to use the path?
In: 77
On a vehicle, the return path is generally the metal structure of the vehicle, sometime referred to as ground (but has nothing to do with real ground, or water for the matter). This allows to run a power line to an item and let the current go back to the generator through the vehicle chassis instead of using additional wires. But in some case is still preferable to use wired return path instead, especially for high power applications or on vehicles that are not mainly metal-made.
On land, you have the power wire and the return wire, altho in AC they are named differently, still that power flows to the user form a wire and back to the powerplant in another wire. Because as you say, ground is not a reliable conductor. In this case the word ground is used for an actual wire to the ground. But this ground line is used to dissipate whatever charge escapes the normal system. This provides a backup path for these “leaks” and usually is enough to prevent accidental electrocution of people, and prevent/mitigate electric fires, in case of faulty or damaged circuits.
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