So is there fancy internals in the switch that choose where to run the current? Out on the ground line vs the neutral line?
>AFAIK no switch or appliance runs more than microamps into the ground line. It's probably a violation of some U.L. rule.
Any reason other appliances don't require such a fancy switch?
>It depends on how much they are asking the switch to do.
Running extra wires is so costly and electronics nowadays is so cheap that they can squeeze quite a bit of performance from one, two or three wires. Or they just go wireless.