I think people should recognise that the taxi market has an advantage. It's a distributed system and a market. Taxis organise themselves.
If you're going to replace an entire market with a centrally planned system and a giant electricity and compute eating machine then you better have something to show for it in terms of efficiency.
What's especially interesting to me here is how the landscape has changed since Uber launched 10 years ago. In 2010, you legitimate had to build a lot of your own stuff; at that point Amazon hadn't even launched SNS or Redshift. [1] Docker didn't exist. Etc, etc.
So the question for me isn't, "Can Uber justify their apparently large infrastructure?" It's more, "If somebody started an Uber competitor today, how much of the work could they get from open source, PaaS, and SaaS providers?"