The worry with black boxes is the false positives these thing can give, I don’t know for sure having never ever having one but I can imagine the speed bumps, not to mention the pot holes, in my road could easily be mistaken for bad driving because no matter how slow you go over them they rattle your bones and shake your brain.
There are quite a few reviews/comments floting around the net, particularly on FB stating this along with swerving around potholes, which has led to numerous users having 2 weeks in the red, thus have been removed from the scheme.