Addendum while I am thinking about it. Arriving in Arequipa, I had planned to use the official taxi booth inside the terminal. However, upon arrival, it was closed, even though I arrived on a normal flight arriving in the afternoon. I used Uber which works ok. Similarly, upon arrival in Cuzco, the official taxi booth was closed as well. Here, I had a ride arranged by my hotel. I haven't tried Uber yet.