Tried Uber again today. Apparently the number of cars has increased significantly. Wait was only 5 minutes. In the past it was more like 15. No Taxi or TaxiLux, but I got a black car. It was a very nice nearly brand new Ranger Rover nicely decked out. The fare was about 30% higher than a hailing a taxi on the street.

Also the driver said that some companies in addition to MK have signed up. I also learned that MK has a fixed fare to/from Narita of Yen 17k plus tolls. You have to book this directly through MK. The Uber fixed fare to Narita is higher.