Lights get you noticed even if a car's headlights aren't pointed at you. This happens a lot -- cars approaching from side streets, exiting parking lots, drivers who had just parallel parked and are at least smart enough to check their mirror before opening their door, etc.

That's probably the reason, yes. That and people think that biking is supposed to hurt simply because it's a physical activity, so they never suspect that the pain they're feeling is because the bike size doesn't fit them.