People tend to do quick cost-benefit comparisons of bednets vs metallic screens, and make some large mistakes. Bednets are temporary, protect only against anopheline mosquitoes which bite at night, and are used only about one-third of the time. One of the reasons for their misuse is that they are suffocating to sleep under.
ON THE OTHER HAND screens with coverings on walls or ceilings, are permanent, protect everyone in the house 24-hours a day, and protect against many blood-sucking insects as well as the ubiquitous house fly which spreads all manner of diarrheal diseases. Screens keep out Anophelines but also Culex and Aedes which bite during the day. They transmit a number of tropical diseases such as dengue. filariasis, Rift Valley Fever. Houseflies transmit pathogens from feces to food; a long list. So if we take a good look at screens from the point of health in general, and not focus myopically on malaria, bednets are a waste of time and money.
FINALLY when the walls and eaves and ceilings of houses are covered with wall paper or even papyrus, and when good screens are put on the doors and windows, and springs are put on the doors to keep them shut, the house increases in value. Also most of this work can be done by the homeowner or local carpenters.
So an accurate cost-effectiveness comparison between screens and temporary bednets should include all of these other factors. You will find that screens are a smart idea.
I use bednets when I camp out for a short time in areas where malaria transmission is intense, but I would never ask my family to live in a house in the tropics where their only protection against blood-sucking insects were a bunch of temporary bednets. So why should we expect African parents to use temporary bednets ?