Really? On par with Uber? Because that's the goalpost that's been set, here.
Hailo was often fully booked when I tried using it, and I had several previous-day reservations evaporate into thin air. It wasn't (as) reliable.
London taxis have always been slightly better than the FR/ES/BG/IT taxis I've taken, but not that much better. And the apps have either gone bust, not worked, or both.