Left hand drive lights have the light focused with a high pattern on the right side (to see road signs I guess). Right hand drive lights are the opposite. So if you have RHD lights on your LHD car you may blind oncoming traffic. Supposedly, this is done with a plate installed inside the right headlight (for LHD) that changes the pattern. I think that many who have the RHD headlights simply adjust them down a bit to minimize (but not eliminate) the effect.