It depends on the body style of the vehicle, generally only vehicles with more vertically-oriented rear windows leave the factory with rear windscreen wipers (hatchback, station wagon, minvans, sport pickup etc)

 

I'm from the warm tropics of northern Australia, so unfortunately, I don't even know what snow looks like, let alone what it's like to have my rear window covered in it

Does your vehicle have reversing camera? The wikipedia article says it does. Perhaps you can learn to trust what the camera is feeding you. I operate very heavy machinery (400 metric tonnes and more) and I can speak from experience that it takes a lot of practice to "trust" the reversing camera.

I'm a car enthusiast (it's my other hobby aside from video games) and in my opinion, to add rear windscreen wiper will be costly and possibly not worth the hassle.... Drilling hole for the wiper assembly, retrofitting a wiper motor inside your bootlid, repainting, running 12v for power, adding a switch in the cabin to activate it, etc. etc.

I have personally never seen a kit before to achieve this (that's not to say they don't exist though) Good luck though!