Why is it necessarily true that all charges occupy themselves only on the surface of a conducting sphere, and not anywhere inside the sphere? One argument is that if a charge were to be inside a conducting sphere, then it would exert forces on other particles inside the sphere and there would be internal currents.
Now, my question is - do we have experimental evidence in every case that there are no currents or magnetic fields generated when a charged conducting sphere is held stationary with respect to another body? Or is our reason for believing that there are no charges inside the sphere of a more mathematical and theoretical nature?
I was discussing this with someone and they brought up Gauss' Law, but it seemed to me that the law is predicated on there not being any $E$ field inside the conductor for there to be no charges, which seemed like a somewhat circular argument. A counterargument was that the charges inside a conductor may exert forces, but it may not always end up producing a steady current flow.
I admit my question is of a very qualitative nature, but what are some strong reasons for why we posit that there can be no charges inside a conducting sphere?