The rain is not showing on the windshield as you can see in the photos (one photo during the day and one at night). The weather conditions for the example are “Torrential rain”.
As you can see, the rain is showing on the side windows, but not on the windshield.
As an example, in the same race and track conditions, I have uploaded a third photo with the Porsche #92 Porsche GT Team 911 RSR (2017) and you can perfectly see the rain on the windshield, with its drops and reflections on them.
