Maybe I am underestimating Uber, but when I think of enormous scale, in terms of number of transaction per day, I think Amazon, or Mastercard. Uber? The upper

Maybe I am underestimating Uber, but when I think of enormous scale, in terms of number of transaction per day, I think Amazon, or Mastercard. Uber? The upper bound of transactions is restricted to the total number of cab rides a day. That number isnt in the billions is it?