To me it just seems more logical to do one wiper, and put it in the center.
-Only one setup- one wiper, one moving motor/mechanism, less power needed, less to break, so on.
-No need to hide it or have extra electrical to pull it away.
Depending on the mechanism, or how hard it would be to change, the single center blade could work for left and right. I know the upper corners would be missed, but that seems superficial to the benefit. It might just be me, but I also think aerodynamics look cool
