Purple headlights on a hearse
Why purple lights for funerals? Funerals are often accompanied by a procession of cars following a hearse with purple lights to let other drivers know that a procession is taking place. Red and blue lights are associated with emergency vehicles, and yellow is typically on construction or utility trucks, so purple became the color of choice for hearses and flower cars. Aside from this, purple emergency lights are rarely used for any other purpose in the US.