IoD: Left/Right View Rear Cameras in Cars for Backing Out of Parking Spot

This probably falls into the "I just haven't seen it yet, but I'm sure it exists" catagory... Why don't cars have cameras pointing to the left and right of the bumper so that you can see oncoming vehicles when you are pulling out of a parking spot and blinded by two large HumVee's with tinted windows blocking your view. I've seen purely rear view cameras to make parallel parking easier, but nothing for backing out of your general parking space.  Sure, accidents could be avoided if people driving in parking lots did so around 5-10MPH, but generally these people seem to speed through around 20MPH.  It's those people I want to be able to see coming and I'm sure my bumper would have a good view before it gets tagged. :-)