Sacto, I hear what you say.
Based on the wiring diagrams I have, VW did not have a dimmer relay until 1966 and did not have any other relay in the lighting circuit through 1975. That's as far as I looked.
No doubt, best practice might be to install SPST relays on both the hi and lo beams, but VW didn't find them necessary.
I suspect that the corrosion comes from the fact that the switches are not sealed and water gets in there. Corroded contacts burn. Mine were not destroyed, just corroded up and blackened. If I exercised the switch I could make the lights come on. I did drive this car 700 miles home, in a thunderstorm all the way, in 2017.
My car was built in 2009 and now has 15k miles.
The headlight switch is rated at 30 amps; same rating as the relays. VW built 20 million bugs at least several million without additional relays.
If the headlight switches are prone to fail or if the wiring harness burn because of the switch, then I'll install the relays. Please advise me if that is the case.
I don't recall this being an issue in the 60's