While I certainly do not disagree with your statement, the designers did not make the other surface flat and smooth, they gave it ridges. -see attached picture-

By the way, I think the most pitted surfaces were the blinkers contacts, and those were working fine. Then again I didn't check the schematics to make sure which was what.

I think the root cause of failure is not the arc, but the oxidation creating too much resistance and preventing contact.

I thought of polishing more, but removal of material seemed to me a worst plan, maybe brazing or soldering some material (some Pb solder might work) and then polishing would have longer lasting effects.

I'll let you know if and when it fails, let's see how much the repair lasts.

If someone knows what product to use to prevent or slow down the oxidation and still allow good electrical contact, I would add that to this repair.