Switches and slide switches in general - - -
Different contact metals are used for different voltages and currents.
The low voltages used to power RX's and servos call for a low voltage switch, not on intended for use
at say 120v.
The higher voltage switches often use contact materials that are designed to reduce pitting, etc. when closed
using the higher voltages. They can oxidize when used at voltages that do not keep them clean.
Low voltage switches tend to use contacts that are made of softer material, don't oxidize as easily, and can be damaged
if used with higher voltages.
Classically, the low voltage contact was gold plated, and the high voltage contact might have used a silver cad oxide contact.
Since Cadmium has a poor reputation, I'm reasonably sure that it's not commonly used these days. Not sure what replaced it.