They used to have rear-wipers on smaller coupe-like cars. I had an old Toyota Celica (from sometime in the 80's) with a really low-sloping rear window that had a rear wiper.

In my opinion, I don't feel that I need one in this car (HCH II). The rear window is not that large and not too sloping. Then again, I've only been driving it for a week! It rained cats and dogs today and I did not miss a rear-wiper.