Parking lights first appeared on cars in the late 30’s. Their original purpose was when parked or broken down on the side of the road to warn other traffic. People soon realized that they also offer slightly better visibility at dusk or dawn, as well as foggy and rainy conditions.
And then in the sixties they figured out that people were confused by the small parking light, thinking it was a car with headlights only further away. The parking lights were changed to amber. People drove with the new amber parking lights to show off how they had a new sixties car.
And that’s why people drive with their parking lights on today.