At least, that is what Stefan van Keulen experienced during a heavy rainstorm, when he could hardly see the cars in front of him because they did not have their tail lights on. “Without you realizing it, other drivers can hardly see you, because the lighting device ‘assumes’ it’s daytime. My advice would be to stop relying on the lighting device.
On a foggy or rainy day, you should always turn on the lights yourself, and, if necessary, the fog lamps too.”