I noticed it in a large tourist-destination US city recently. You literally could not get an Uber from the airport (which is not at all far from the city center

I noticed it in a large tourist-destination US city recently. You literally could not get an Uber from the airport (which is not at all far from the city center). Instead, drivers have formed an informal co-op, negotiating prices and dispatching in person or by phone. Basically an uncredentialed taxi service, that the city was looking the other way on because someone has to do it, and people still won't use the traditional taxis out of a habit - they go to the ride share pickup area, try to call an Uber or Lyft, can't, and then go to the grey market option out of desperation.