It's hard to imagine that someone would run into someone hard enough to damage something and just make a joke about it. I can understand someone having trouble driving (as the writer of the article mentioned, some of the rental equipment has little "quirks" that even an experienced driver might not figure out for a while), but I would be absolutely mortified if my DD drove into anyone. That's one of the reasons we have not taken her power wheelchair yet to WDW; we were not sure how she would react to the crowded difficult conditions at WDW.
A few months ago, she had a good trial though. We went to the "Harry Potter" party at a local Barnes and Noble when the new book came out. She did really well driving in the crowded conditions. Other than a woman who was taking a picture, backed up crouching to get her whole party in the picture and came to a stop about an inch from landing on DD's lap. I yelled, but the woman didn't look back or anything. DD stopped driving, took her hand off the joystick and just sat there patiently waiting for the woman to finish. I don't think the woman even knew what almost happened. What I can't figure out is why the others in her party didn't say anything to her. I was just hoping the woman didn't land on the joystick if she fell.