I guess whatever reason it is local, because last summer drove from Lisbon to Berlin and this summer drove from Berlin to Milan and every time I stopped at a gas station I had to clean the car because boy did it have A LOT of dead bugs.
Anecdotally, I hardly had to clean my windscreen when I was living in a city. I'm living in a small town with fields all around it now and I never have a clean windscreen anymore. However nothing like the one in the first picture of the article. That's how my front license plate looks like.