I just had a pad whose wear indicator broke off and so damaged the inside face of the rotor along the outer edge. I'm definitely going to get this rotor resurfaced, but should I resurface the drivers side? I don't think its necessary, since the calipers will apply individual pressure and I don't think a rotor on one side of the vehicle would affect the other. Am I correct?
A newly resurfaced rotor may brake differently than a bedded in rotor. If different enough, you may find that the vehicle pulls to one side during braking. This would diminish over time, but could lead to the vehicle veering off, especially in a panic situation. I recommend having both rotors turned.
The difference is so minimal that it's not going to make a difference; however, many modern cars these days have rotors that are so thin that resurfacing isn't possible.
If you do end up replacing the rotor, consider doing the pair just so you know that both sides are of the same make, model, wear etc.
I think that the rotor will be beyond its lifespan when badly damaged like this anyway. Thus exchange for a new one will be likely required. As a rule of thumb, I always replace these components in pairs (brake pads, rotors, drums).
Or, you can have the single rotor resurfaced (which isn't usually expensive) and then measure the thickness.