When your vehicle is correctly parked on the side of the street, other road users will approach your stationary vehicle from the rear or from the side. At the rear, there are usually red reflectors integrated into the tail light housings. If the tail light housings are clear, then there should be red reflector inserts in the rear bumper cover. Same for the front corners. If the front corners are clear, there should be amber reflector inserts in the front bumper cover. The reflectors in the light housing or on the bumper covers is the only way your parked vehicle is visible to other road users on a really dark street at night. Do not eliminate both. (Yes, I know about the European parking light)