Agreed. Speaking from experience, dirt/dust can really block off visibility... This includes rear facing cameras. The rear wiper is what allows you to see behind you in those conditions.All the people saying they don't need a rear wiper probably aren't driving in really dusty areas or on salted streets in snowy places. A rear camera or window without a wiper becomes useless within a couple of minutes with salt spray coming off from under the vehicle.
Also what this isn't testing is all the crud that doesn't melt that will eventually find its way into that cavity. The heater will pass with flying colors when testing with clean water only.
They need a defrosting ring around all of the cameras and a spray nozzle to clean them off. Otherwise none of this autonomous stuff is going to work, unless LiDar can really bridge the difference. Does it work well if the sensor is covered in snow and ice?If anything, I would rather have a good rear glass defroster and rear camera clear of debris or ice.