Question

Why do charges does not reside inside a conductor

Answer 1

Because charges move continually and when connected with some ckt they flow through the circuit and when not connected.. they do not flow

Answer 2

The reason for this is that in a conductor the charges are mobile( ie. they can move) so in order to minimise repulsions the charges spread throughout the conductor and they can be farthest if they are at the surface...

I hope this helps you...