Problem with snow and rain on the windshield

This is seriously immersion breaking for me. And not only snow or rain, overall the windshield and its behaviour / graphics is either very poorly made or bugged. In most of the cars, even if you set wipers to manual - the windshield somehow magically cleans itsself. What i mean is, that the main part of the windshield where the wipers can reach is always clean, and only the outside parts of the windshield get some kind of dirt on them. So even if you have wipers on manual and you dont use them, the window stays clean. In some cars, the window gets a bit of dirt if you drive very very long stage, but mostly nothing. What is the point of having wipers in the game and what is the point of having setting to turn them to manual, when its basically useless