This thing was parked next to me at the local Home Depot on Saturday. I can't say I've ever seen them before. He didn't even need a sidestand. I wouldn't want them going through the Dragon, or any other road for that matter.
I saw these at a Cycle World motorcycle show a few years back in Chicago. They seem like a reasonably priced add-on I could see if someone had medical issues but didn't want to go full trike (look up the price of a full trike conversion )