Johnny Boy, R=0 only in case of steady currents. So, you set up a current and then see if
Delta V = 0 in the limit t --> infinity. Superconductors don't have zero resistance to nonsteady curents.
How do you verify that R=0? You take a normal metal wire with R>0 and you let a current flow through it. You then connect a supeconductor between two points of the wire. There is a voltage difference between the two point before you connect the superconductor. After you connect it the current will flow through the superconductor and bypass the wire. If you then measure the voltage between the two points you find that it is zero.
So, even though the initial voltage difference was needed to cause the current to flow through the superconductor, once the current flows through it, the voltage difference is zero.
I admit that my knowledge of superconductivity is incomplete. I don't work in the field and I studied this topic a long time ago. However, you don't understand some of the the basics of electrodynamics which makes any criticism you have about superconductivity highly suspect.
