As soon as I read your first sentence I immediately thought "I wonder if they live in Germany".

Having lived there a few years I was astounded at the lack of fly screens, given that there are just as many mozzies and other bugs flying around there in summer as there are back home in Australia. But in Oz, pretty much every window on every house has a fly screen.

I think I saw two or three in my entire time in Deutschland. So I know they're available, but I don't get why they're so unpopular.