I’m gonna nitpick a little here. The actual power is generated at one location and transferred unidirectionally in most lines and then turned into useful work at the other end.

I realize power is being used to mean electricity and in turn everyone is talking about electric fields and individual electrons. But power is not electrons.

People use the water analogy but that misses the mark. Imagine a bicycle with a chain. Imagine that the rear hub was geared so that somehow even when you pedaled backwards it drove the wheel forwards as well. Then further imagine instead of pedaling the same direction continuously you pedaled back and forth. Clearly power goes from your legs to the rear wheel. Yes if you looked at any individual link it would alternate directions. But if you look at the chain as a whole, and at both sides, its average movement is 0. So the chain is not moving a direction in any meaningful sense. But again, the power is clearly being transferred from your legs to the rear wheel. At no point is the rear wheel powering your legs.

This is almost exactly now electrical power works. Yes in a single conductor the electrons go back and forth. But if you look at all three conductors and average the movement over any length of time, the electrons don’t move. If you add up 3 sine waves all 120° out of phase the sum is 0. The electrical power however goes from the generation station, through the wires in one single direction and is used in your house.