Taxi Driver pops up from time to time, presumably used by NTA/TfI to test systems or such like. I guess there's plenty of plausible explanations for the Js, maybe the drivers just didn't bother registering with the app, maybe they were renting under the counter, maybe they are among the 20,000 that Joe Heron told the media had left the trade for better (paid) jobs coming back, etc... or, maybe, they're recycling badge numbers?